This is a block that is cast from plaster using a laser-cut wood mold, which gives the plaster a unique texture. The plaster block is encased in wood for variation of color and texture. The block that I made measures 1.5" x 3" x 6", but you can adapt these instructions for a project of any size.

What You Will Need:

Materials

Panels of 4" x 24" x 1/16" Basswood
Panel of 4" x 24" x 1/8" Dark Wood (Mahogany or Walnut)
Scrap wood (at least 1/8" thick) for outside of mold
Strong Tape
Wood Glue
Plaster of Paris

Tools

Large flexible bowl
Small flexible cup
Wooden spoon
3D modeling software (such as Rhinoceros)
Laser Cutting Machine

Step 1: Create Your Mold on the Computer

In Rhinoceros, I started with a solid block, and then created an undulating void inside the block.The final size of the block is 1.5" x 3" x 6", so the interior (plaster) part of the block should measure 1.25" x 2.75" x 5.75". after I was happy with the form, I sliced the block every 1/16 inch to create guidelines for the laser cutting machine. I traced the edges of the block along the solid/void line to create a template for the 1/8" thick wooden shell.

Place the cut lines on the appropriate template for the laser cutting machine that you are using.

Step 2: Print & Construct Mold

Construct a box to pour the plaster into. Tape the edges of the box to prevent the plaster from leaking out. Glue the pieces of the mold together, into 1/2 inch sections.

Step 3: Pour Plaster

Use 2 cups of plaster for every 1 cup of water. Mix the plaster in a flexible cup, and pour the plaster into the mold. Remove air bubbles by gently tapping the mold on a tabletop. Wait at least an hour for the plaster to set.

Step 4: Remove Wooden Mold

First, remove the outside of the mold. Let the plaster continue to dry for a few more hours before removing the interior mold. When you are ready, get the interior mold wet and gently pull it out in segments. If you are using complex geometry, you might have to peel off each piece of wood, one-by-one.

Step 5: Glue Wooden Shell

Use super glue to attach the wooden shell to the plaster form. You might have to file the plaster down to size in order for it to fit within the enclosure. You can treat the wood with a varnish, or paint it at this time.