Having a nice flat surface to work on, I decided to start building up the gantry. I printed out some screenshots from my solid model and wrote in the dimensions by hand, not wanting to take the time to create all the dimensioned drawings in the CAD software. Then I got busy cutting out all the pieces of plywood on the table saw. I used a dado set for cutting the slots in the top and bottom pieces.
I took this image to show how the pieces will fit together. The top is slid back slightly for better visibility:
Next I cut out all of the web pieces from 1/2″ MDF. Here are all the gantry pieces laid in place for a test fit:
Once again, I glued the pieces together in stages to make sure I could keep everything aligned properly. The number of clamps available also limits how much can be done at once.