The Pattern for the fine feed housing was made from what ever I had in my garage. It turned out to be a piece of laminated particleboard. The cuts were a little rough, and could have been coated with wax or epoxy, but I decided that for this application, finish was not critical. I drew the part in TurboCad2D and then made the pattern from the print.
This is a shot of the pattern in the mold. It took three tries to get the mold cavity right. I didn't have enough relief in the pattern, so I kept breaking the edges of the mold when pulling the pattern out. Finally, I rammed the mold lightly and the pattern came out. There is a fine line between a tightly packed mold and one that you can get your pattern out of.
A shot of the R2 unit in blazing glory.
The most joyous moment of casting a part: cracking open the mold to find out that the part was a success!
The housing hot from the sand shakeout.
A little finish machining and the housing will be ready to bore out for the worm gear.