Introduction: SOMA Couch

About: I'm a web developer and I enjoy outdoors a lot

One day I have been given a SOMA cube which is a three-dimensional puzzle composed with 7 pieces, all different. There are many ways to solve this puzzle and many goals to achieve. The most classic one is a 3x3x3 cube, but you can also form a duck, a plane, etc. and even a couch!

Since then I always wanted to build a huge replica of it in order to use it as real chairs or couch. The result turns into a 120x120x120cm cube!

I'm working in a very cool and professional company named Nearsoft, that financed this project. Now the SMOA cube pieces bring happiness in the large meeting room of the office!

If you're interested in knowing how I built it, stick around!

If you like this project feel free to vote in the Furniture Contest!

Step 1: Bill of Material and Tools

For this project you will need a lot of plywood and other materials:

  • 7 sheets of 5/8" x 4' x 8' pine plywood (the most economic you can find)
  • Wood glue
  • Lots of 1" wood screws
  • 8 sheets of 1" x 4' x 8' upholstery foam (the denser the better)
  • 3 gallons of foam glue
  • 7 pieces of 8' canvas fabric, each piece with a different color
  • 7 pieces of 2 meters long infinite zippers, that match colors with the fabrics
  • Thread

And some tools:

  • Circular saw
  • Table saw
  • 4 F-clamps
  • 4 C-clamps
  • Square
  • Cordless screwdriver
  • Sharp knife
  • 4" brush
  • Respirator mask
  • Cisors
  • Iron
  • Sewing machine

Step 2: Cut the Plywood Sheets

You can download here the Sketchup 3D model of the SOMA couch and the cutting layout of each plywood sheet. You can also find an Excel spreadsheet listing how many parts for each piece of the puzzle, and their location on the layouts (parts.xlsx).

The final 120x120x120cm cube is composed of 27 40x40x40cm littlevirtual cubes that have 1" of foam on some faces. The plywood parts won't match the final dimensions of the couch because of this thick foam. The 3D model take into account this important aspect of the build.

In the 3D model each color represents a different part.

Set you circular saw to cut to 90° angle and start ripping all the sub-parts from the plywood sheets. You can sometimes cut 2 parts at once like in the pictures. The "L" shaped figures can be ripped as straight bands then glued 90° together (see pictures). It makes the bevel cut very easier to performRea.

Then, set your table saw to cut to 45° angle and cut the bevels.

The 11 "L" shaped parts (LA, LB, LI in the spreadsheet) will need a spline to make a strong joint, cut it the way you want (I used a spline jig on my table saw). I'm using scrap-wood for the splines.

Step 3: Assemble the Sub-parts

Put some glue and assemble the 11 "L" shaped parts. Lay them down on a flat floor while the glue dries.

The joint don't need to be perfect, as long as they are strong (they will be covered with foam).

Parts 1x2C and 1x2D referenced in the spreadsheet also need a sub-assembly. I simply glued them together, no need for spline here since the 45° angle provides a larger contact area. To maintain the pieces while the glue was drying I screwed the smallest parts down onto my "working table" and clamped the largest ones (see picture).

Once the "L" shaped parts are dry add a reinforcement with scrap wood on the inside face. It might not be strictly necessary but it takes no time and makes the joint even stronger.

Step 4: Make Some Fixtures for Clamping

It's easy to make small wooden fixtures that will allow you to clamp 2x45° faces with only 3" C-clamps!

I just ripped a scrap of plywood and a 2"x2" piece of square wood, glued and screwed together, then cross-cut into 8 pieces (see picture).

To use them just screw them square on your workpiece, oriented toward the joint, and use some clamps to press the 2x45° faces together. It's fast, efficient and quite precise!

Step 5: Glue All the Parts to Form the 7 Pieces

One by one use the fixtures to glue together the parts and create the 7 volumes/pieces of the puzzle.

Use the spreadsheet to identify which part goes where.

I used screws to maintain the pieces together while the glue dries, this allows me to move very fast to the next joint.

Step 6: Cut the Foam

Cut strips of foam using a sharp knife. I made myself a small jig to speed up that process.

Use the pieces to measure the width of the stripes, some of them need to be 40cm wide, some other a bit narrower (2" less). Make sure that all the wood will be covered with foam. The small side must measure 40cm.

The cut don't need to be extremely precise, you can reuse small bits together, in the end all this won't be visible as it will be covered with canvas fabric.

Step 7: Glue the Foam Onto the Pieces

For each faces we want to glue the foam now.

Pour some glue on the wood, be generous! With the brush spread the glue as much as you can. Then apply the foam and maintain it there a minute trying to apply even pressure on its surface. The glue should stick quite quickly.

Make sure you overlap the foam on the corners. At the end no wood must be exposed.

Use a mask to protect your lungs, this glue is nasty!

Step 8: Sew the Covers

I don't have pictures of this part of the process. It's quite straightforward though. Cut the canvas measuring on top of the pieces, accounting for sewing overlap. Try to visualise where to put the zipper so you will be able to slide the piece inside the cover. Iron the fabric and sew the pieces together. Regular sewing stuff.

If you want to learn or improve your skills, take the machine sewing class!

Step 9: Slide the Pieces in Their Cover

This sounds silly but this might be the most stressful step! The covers need to fit tight and the pieces have awkward geometries, sliding them is not that easy!

Hopefully the foam can be compressed which makes it a bit easier sometimes as the canvas is not stretchy at all.

Step 10: Conclusion

This couch is quite comfy, not so heavy (thanks to the hollow pieces), it can be moved around, changing shapes and overall color, and very very fun to use!

During the meetings the parts can be spread apart, each one providing sitting surface for multiple folks, sometimes even providing elevated surface for a laptop or arm resting!

If the fabric gets dirty, you can unzip the cover, remove it and wash it in a regular washing machine.

Even though it takes a lot of material and time to make, it's not very difficult and the result is surprising!

If you like this project feel free to vote in the Furniture Contest!

Feel free to comment, bring suggestion, ask questions below!

Thanks for reading.

Furniture Contest 2018

Participated in the
Furniture Contest 2018