Tips & Tricks 33

These instructions will give you suggestions on how to use the rubble block mold and also describe a few of its quirks.

Click on the tower to take you to the Dice Tower Building Instructions page.

About the #263 Rubble Block Mold


Here is a photo of the blocks from one casting of mold#263. Click on the photo for a larger view.

These blocks were made by actually breaking and assembling broken stone to form each block. Because of the deep cracks and sharp edges of the stone, these blocks have to be cast with their main surface texture face up.

If I had tried to make regular full building blocks with this texture on the sides, you would have ended up with an awful amount of air bubbles in your castings.


Each block is accurate to 3/1000th of an inch in size. However, because each block is made of actual broken stone, the side edges have an irregular shape.

This will make stacking the blocks very challenging because they will not want to stand up straight on their edges.

If I had sanded the edges and textured them to make them easier to stack, the texture would not have blended in with the rest if a block was turned on its side.


Because of the irregular side shape and the fact that each block is only 1/4" thick, you will need to use extra glue when gluing the sides of the blocks together.

I strongly suggest using Aleene's Tack glue. This glue is very thick, dries fairly quickly and is a bit flexible so your walls may bend a little at the joints rather than cracking apart. You can find it a most Wal-Mart stores in the craft section.

Rubble Block Building Methods

What follows are a few strategies to help you with the stacking problem.


Method 1 - Making full blocks

A fairly easy way to build using these pieces is to glue blocks back to back first. Then you will have full blocks that you can stack and build with.

This takes extra time and you only get half as many blocks with each casting of the mold.

It's best to use a guide such as a corner made of Legos when gluing the blocks back to back. This will help insure that the blocks are glued together squarely.


However, for some projects it's very helpful to stack up the blocks to determine room size and where the placement of windows should be. For many people, this is the method they usually use when planning buildings.

As you can see, even though full blocks are easier to stack, the edges of the blocks may still be a little uneven, so stacking a large flat wall may get a bit precarious after the eighth row or so.


Method 2 - Making a straight wall slab

This method is probably the easiest to plan and build with. With this method, we are making each wall a 1/4" thick slab with straight sides.

This method takes fewer blocks and getting the sides straight is fairly easy. You simply place a ruler or straight edge of some kind along the edge when gluing.

Notice that I put spacer blocks in the doorway to keep its size correct. These blocks would not be glued and would be removed after the wall dries.


When assembling your room or building, you simply glue the walls against each other on the corners.

Click on the photo to see a close-up of the corner after painting. You can see the straight seam bit it's not too noticeable.

Painting instructions are further down on this page.


Method 3 - Interlocking wall slabs

Looking for a challenge? This is the most difficult method of construction. Each wall slab will interlock with the other walls on the corner.

For this to work out, you will need to put spacer blocks on alternating rows to hold the place where the other wall will fit. These spacer blocks will not be glued and will be removed after the wall dries.

This method will give you the most realistic look, but it's also the most difficult to figure out the size and spacing of each wall slab.


Once the wall slabs are dry, you will need to test fit them together. They will most likely not mesh perfectly the first time.

To fix this you will need to determine which block is getting in the way and use a hobby knife or file to trim down the edge of that block.

This is why I suggested using a lot of glue on the joints. Trying to wiggle two wall slabs together will cause stress on the wall slab. If you don't have enough glue, the wall may come apart at a weak joint.


Click on the photo to see a close-up of the corner after painting.

I think that this method will give you the most seamless and realistic corners on your buildings.

Painting instructions are further down on this page.


Method 4 - Glue onto a solid surface

This method works really well for retaining walls or adding texture to a large flat surface such as a mountain side.

The difficulty lies in getting the corners to work out if you have odd angles or several corners in a series.


The top foam was carved down and ground scenic materials were glued to the top surface for the grass and foliage. Painting instructions are further down on this page.

Click on the photo to see a close-up of this retaining wall after painting.

This method can be used to add surface texture without adding a lot of weight to the model.

If you have very large surface areas, you might consider using mold #262 instead. This mold has larger wall slabs on it, so you don't have to assemble as many pieces to make a larger wall section.

What Do I Do with the Back Side?

This is a really good question. The outside of your building may look good but what about the inside? Below are a few suggestions for how to dress up the back side of these wall sections.


Method 1 - Don't do anything

There are many projects that you really don't need access to the inside of the structure. The most used example would be a fireplaces and chimneys where the inside painted flat black looks perfectly fine.

Other projects include small areas such as steps and walkways. I included the sand blasted block on this mold to especially be used as steps in combination with the stair builder block (shown in the upper left).

Another project where you don't need to access to the inside is the dice tower shown on the right. You can find instructions on how to build this dice tower on the Dice Tower Building Instructions page.


Method 2 - Glue on more blocks

Here I have already assembled and painted the outside wall. What I am showing you is that you can simply stack and glue blocks onto the inside of the wall after the outside is fully assembled.

This is much easier to do after the outside is assembled and standing there. You can also get the windows arches to line up from front to back easily.


Method 3 - Line it with something

Here I'm going to line the inside with foam sheets used for crafts. I found these in the craft section at Wal-Mart.

This stuff is about 1/16" thick, flexible and easy to cut with scissors. Sometimes you can find the stuff with adhesive on one side but if you can't, just spread glue on the inside of the wall and position it in place.

I'm using a buff color but maybe white would have been better. You can also paint it if you want a custom color or some sort of texture on it. If you can't find foam, other materials that could work are painted card stock or construction paper.


Once it's dry, take a hobby knife and trim up the outside and the windows.

You'll notice that I have glued the liner in after the outside stone has been painted. This keeps you from getting paint all over the inside liner. I have instructions for painting the stone further down on the page.

Be careful when trimming out the windows. I ended up poking my finger a few times while doing it.


After the foam is trimmed up, you can just leave it like this. However, I'm going to add some planks to the sides of the walls.

The planks shown here are from mold #225. These come in standard lengths and sizes. I have pre-painted them and instructions for painting them are shown further down on this page.


I simply glued these planks onto the insides of the wall. Click on the photo for a larger view.

The advantage of gluing onto foam is that you don't have to worry about covering up seams. You'll understand what I mean after you look at using the panel molds below. Since you are free to put planks where ever you want, you can get pretty creative on how to decorate your walls.

The downside is that the foam will take up 1/16" on each side wall and the remaining distance will be some odd measurement. You may have to trim up certain beams to allow for the foam thickness.


Method 4 - Use panel and timber molds

The stucco panels shown here are cast from mold #251 and the planks shown here are from mold #225

I have pre-painted these so they are ready to glue onto the inside of the wall. The painting instructions can be found further down on this page.


You may choose to use the panels because they add a nice texture to the walls rather than having them smooth. However, using panels alone will not fit the walls well. That's because the panels are only in 1/2" increments.

Luckily we also have the timbers which are in 1/4" increments to fill in areas and spread the panels out.

You may notice one problem with this method though. Currently there are no round top arches in wood to match the outside of the stone. To deal with this, I am simply going to frame the inside of the window square and leave a little bit of the stone showing on the inside. The windows will be so deep that you will probably not notice this anyway. The other option would be to simply plan you house with square windows to begin with and not use the round stone arches.


Next I will glue on beams to cover up the seams in the panels. This is not too difficult because the planks come in standard lengths to fit most spaces.

Also, feel free to glue beams on top of beams. No one will know that two beams were glued right on top of each other.

Now this wall has a nice stucco texture and beams that cover up the seams. You can see the backside of the stone at the top of the doorway but I don't think it distracts too much.

This also allows you to use a rectangular door that opens inward.


Let's try another example. This wall section has a small window in the center of it. On the left, you can see that the panels alone will not fit around the small window in the center.

The second photo shows using the planks to fix and fill in these areas. The timber mold also has decorative wooden pieces on it. I chose to use one of those to fill in under the window instead of the stucco.


This photo shows both walls with the finished beams glued over the seams. Click on the photo for a larger view.

Notice on the finished wall there are a couple of beams placed oddly. These include the upper right side of the doorway, the embedded beam near the upper right of the figure and the recessed wood panel under the window.

Personally, I like using the combination of panels and beams the best. The panels sometimes force you to do a few odd things which can result in an interesting arrangement.

Rubble and Plank Painting Instructions

The projects above will use colors that I already have on the web site. The colors used for these examples are:

Solid Black

Solid White

Earth Tone Medium
From the Earth Tone Painting Instructions

Castle Gray Light
From the Castle Gray Painting Instructions

Earth Tone Light
From the Earth Tone Painting Instructions


Painting the Rubble Stone

For the first coat I am spray painting it flat black. Be sure to do this outside or in a well ventilated area.

Spray painting works much better because the pieces are thin and water based paint will soften the glue.

The trick is to get the paint into all the cracks. To do this you will have to paint the walls straight-on, and also spray from all the angles you can think of. Paint the front and back of every piece.


The second coat of paint is earth tone medium color from the Earth Tone Painting Instructions page. This is sort of a "pumpkin pie" color.

Dry brush this on lightly and when the brush starts to run out of paint, then dry brush heavily.

If you do it right, each stone should have varying shades of brown on it with no black. If you do it badly you will have solid brown stones with no variety of shade on each stone.

Click on the photo for a larger view.


The last coat of paint is castle gray light color from the Castle Gray Painting Instructions page.

Dry brush this on lightly.

This color will highlight the edges of the stone in gray. It will also gray out the brown a bit. After the brush runs a bit dry, you can go a little more heavily but keep it lighter than when you were applying the brown.

Click on the photo for a larger view.


Painting the Wooden Planks

The wooden planks used in the examples above are from mold #225. This mold not only has beams but also decorative panels and a window.

At first, you may have no idea how many castings of this mold you will need. I would suggest one casting per 6" square wall section to be covered. I also suggest that you go ahead and paint every piece instead of trying to only paint what you think you will need.

Before we can spray paint these black, we need to stick these down to a large piece of cardboard. I'm going to use cheap permanent double stick tape. You need the permanent kind or the pieces will not hold down.

Before sticking them down, check the back of your planks. If the backs are concave, then you will need to sand the back slightly with fine sandpaper so they will stick to the cardboard properly.

Simply lay a piece of fine sandpaper on a flat surface, place a plank on the sandpaper and give it a few quick swipes. This is much quicker and easier to do than you may think.

Check to see if your pieces are stuck down properly by taking a wide brush and brush across them with medium pressure on the cardboard. Just pretend you are dry brushing your planks with paint. If they do not come loose from the cardboard then you know they will stay in place when you go to paint them.


The first coat I am spray painting it flat black. Be sure to do this outside or in a well ventilated area.

Be sure to spray from all angles so that you get the sides and ends of each plank as well.


The second coat of paint is earth tone medium color from the Earth Tone Painting Instructions page. This is sort of a "pumpkin pie" color.

If you are using house paint, thin the paint slightly and make the brush as dry as possible. If you are using acrylic craft paint then you may not have to thin it.

If the paint is too thick, you will get solid brown on the top of your planks. If you thin the paint but put too much on, the paint will run into the cracks.

The trick here is to thin the paint slightly, dip your brush in and brush almost all of it off on a paper towel (even more than usual for dry brushing).

What you want are lots of thin coats of paint. When first brushing over the planks, it will not look like anything is happening. This is exactly what you want. Don't go back for more paint but instead keep brushing over the planks.

If the coat of pumpkin pie color is thin enough, the black transmutes through the brown and changes the color completely. Pumpkin pie turns into a dark oak. Remember to brush lightly, keep the paint thin and keep the brush really dry.


When finished, pull up the tape and the planks should come up with it.

Your wooden planks are now completely painted and ready to glue on. The most time consuming part of the whole process is sticking them down onto the cardboard at first.

If you are wondering how many castings you should paint, I would suggest painting one casting per 6" square wall section to be covered.


Painting the Stucco Panels

The stucco panels used in the examples above are from mold #251.

To give you some idea how many castings of this mold you will need, I would suggest one casting per 3" x 4" section of wall to be covered. I also suggest that you go ahead and paint every piece instead of trying to only paint what you think you will need.

Much like the plank pieces above, I am going to stick the panels down using permanent double stick tape. If the backs of the pieces are concave, then you may need to sand them slightly so they will stick well.

First, paint the stucco panel pieces the earth tone light color from the Earth Tone Painting Instructions page. This is a light cream color. You may have to thin the paint down so that it will get into all of the detail.

Once dry, dry brush it solid white.

Here are a couple of projects you can build using the rubble blocks.

The first project is the Rubble Dice Tower. You can find how to make it on the Dice Tower Building Instructions page.

The second project is the Rubble Bridge. This project uses mold #259 and you can find its building instruction on the Rubble Bridge Building Instructions page.