I have used the SOMA Cube puzzle for several years as part of hands on math education programs at

Leonardo's Basement in Minneapolis (leonardosbasement.org). Two big observations from these experiences:

1. The more SOMA cubes you have the more fun they are to play with.
2. 7 out of 10 people will say “Oh! Rubiks cube!”

I decided to put these two observations together into something roughly the size of the Rubik's Cube that has lots of pieces to play with. I call it “BLOKL” a mash up of “blocks” and “puzzle”.
Find out more about the SOMA Cube's history here:
Thorleif's SOMA page - https://www.fam-bundgaard.dk/SOMA/SOMA.HTM
Wikipedia - https://www.fam-bundgaard.dk/SOMA/SOMA.HTM

BLOKL is eight SOMA Cubes which is enough cubes to make another cube which is a pretty logical progression. This extends the SOMA Cube in several ways:
1. The mirror properties of the two “helical” pieces become apparent. (more on this mathy stuff later)
2. The profound similarities of the 240 unique cube solutions is easier to apprehend
3. Now we have got some blocks to play with! Free play with blocks is a good thing.
4. Language art games are now doable. Play with blocks, build a thing, thing is now first clue in a game of “Twenty Questions” - https://en.wikipedia.org/wiki/Twenty_Questions

Step 1: Parts, Tools and Preparation

1. 216 (or a few more just to be safe) - 1/2" wooden cubes I recommend Woodcrafter https://woodcrafter.com/hardwood-cube-5-package-of...

2. Wood glue (I use a Glu-Bot applicator to make small dots of glue https://www.fastcap.com/estore/pc/viewPrd.asp?idpr...
3. Rit Dyes, food coloring or other water soluble colorants. Red, Orange, Yellow, Green, Blue, Violet, Auburn (Brown). Theoretically you can make all of the colors from Red, Yellow and Blue.
NOTE - there is an important reason for these colors in the BLOKL scheme. When recording cube solutions the pieces can be abbreviated by a single letter. More about this in the Activity Guide.
4. Plastic cups and spoons for mixing colorants and soaking cubes.
5. Drying pans. I use aluminum foil roasting pans.
6. 5/8" and 1/2" square dowels about 18" long for squaring up while gluing
7. Somewhere to make a mess. I don't have a shop so I use the bathroom.

Step 2: Color the Cubes

1. Sort out your cubes into cups. Red - 24 cubes. Orange, Yellow, Green, Blue, Violet and Auburn(Brown) - 32 cubes.
2. If using liquid Rit dye stir in about one teaspoon of the dye to two cups of hot tap water.
3. Pour in your cubes
4. Soak for 3 minutes stirring very 30 seconds or so to ensure even coverage
5. Pour off the liquid
6. Add 2 cups of cold water to the cup with cubes and pour out. Just a quick rinse to make the parts less likely to stain things.
7. Place stained cubes in drying tray. The colors intensify with 8 hours of drying.
8. Repeat steps 2-7 for each color.
9. I use a fan to accelerate drying and I highly recommend no less than 8 hours before gluing.

Step 3: Gluing the Cubes in General

I have found after building ten sets of BLOKL that some of the typical wood gluing steps can be shortened or eliminated. All of the BLOKL pieces I have built this way withstood being dropped from the table to floor without breaking a glue joint. Also are holding up to extended sub zero and high 90s temps in my car (I take these to events so a BLOKL or two tends to be in the car more often than not).

1. I use small dots of glue rather than using enough glue to squeeze out of the joint and then clean up.
2. Clamp time. I use about ten seconds of squaring up and and pressing. Then I put the parts aside for ten minutes.
3. I glue modules of two cubes as the base of each shape as much as possible. This prevents having to try and clamp three or four cubes at a time. That would take some pretty fancy jigs and fixtures.

NOTES -
1. Orange, Green, Blue and Auburn are built from two modules of two cubes.
2. Yellow and Violet are built from a single two cube module and on two single cubes
3. Red is built from a single two cube module and one single cube.

Step 4: Gluing the Violet Piece

Gluing the violet piece illustrates some of the steps I described in the "Gluing in General" step.

1. Glue together two cube modules first
2. Use small dots of glue
3. Use the 1/2" and 5/8" square dowels to square up glue joints
4. The final picture shows what this somewhat meticulous method can accomplish. The violet parts mate to each other cleanly

Step 5: Gluing the Blue Piece

I use a different approach to glue the Blue piece. Primarily because I want them to mate together as finished pieces. The cubes are not dimensional perfect some can be off by as much as +or- 0.02". This method allows us to work around that and make pieces that fit together nice.

1. Start with two cube modules
2. Use the 1/2" square dowel to get the parts lined as shown above. Build one part and let it set for at least minutes. We are going to use it as a jig to make the remaining seven parts fit together nicely.
3. Slide a two cube module into the finished Blue piece.
4. One dot of glue.
5. This can be tricky.
a. Press in the second two cube module into the assembly and look at it from all angles.
b. If the glue joint looks solid and the parts fit keep pressing for about ten seconds.
c. Pull away the new Blue piece and set it aside.

IF THE GLUE JOINT DOES NOT LOOK SOLID -
a. Pull the pieces apart and wipe of the glue.
b. Look at the piece you are trying to glue. Are two cubes the same size? If not try gluing the larger of the two
cubes in the module to the on already in place in out Blue piece jig
c. If the two cubes in the module are the same size but the glue joint is offset you may be able to rotate it and
make it fit up.
d. Last resort make some new Blue cube pieces (because you bought some extras. . .I hope)

Step 6: Gluing the Orange Piece

1. Start with two cube modules
2. Single dot of glue
3. Square up glue joint with 1/2" square dowel.
4. Look at the glue joint from al angles
5. Make adjustments if needed (it happens)
6. Press together for about ten seconds and set aside

Step 7: Gluing the The Auburn(Brown) Piece

I use the color name Auburn for this piece so it can use the single letter "A" abbreviation since I already used "B" for Blue.

Gluing the Auburn Piece is very much the same process as gluing the Blue piece

IMPORTANT NOTE!!! - The Auburn piece is the mirror of the Blue piece. Have a look at the "Pieces" section of the Wikipedia article for clarification:
https://en.wikipedia.org/wiki/Soma_cube#Pieces

Step 8: Gluing the Yellow Piece

Similar to the Violet piece the Yellow piece is made up of a single two cube module and two single cubes. Follow the steps for the Violet piece but this is easier because you are making a "Tee" which is easier to square up the joints.

Step 9: Gluing the Green Piece

The Green piece is made of two cube modules. Make the two cube modules let them set for five minutes and then glue them together to make the "L"

Step 10: Gluing the Red Piece

The Red piece is built from a single two cube module and a single cube. Glue up the two cube module and set aside for five minutes. Glue on the remaining single cube to make the "V".

Step 11: Four Unique Cube Solutions Step by Step

Looking at the pictures you likely count eight instead of four cubes being built. However I am using the mirror property of the Blue and Auburn pieces to show that defining what a unique solution is . . . is a bit nuanced. You can read more about this in the activity guide and the many links it provides.

Step 12: Parting Thoughts and Activity Guide

I hope you have had some success building your BLOKL. If you made some mistakes, welcome to the club. I certainly have made quite a few. If you are having fun with your BLOKL and want to share your experience head on over the "BLOKL Building Blocks Users" on FaceBook

https://www.facebook.com/groups/1503493129685016/

Hit me up in the Instructables Comments for questions and suggestions