Project is pretty simple, though time consuming; total construction time was around 4-5 hours. Most of this is making all the rule marks, so if you sacrifice function a bit, you could get construction down to around 2-3 hours.
For materials, you'll need a bit of acrylic or polycarbonate (plexiglass or Lexan), a form holder (try Staples, about 17$), epoxy, crayon, and paper.
For tools, you'll need clamps, a file, a box-cutter, a saw (like a band saw) for cutting the plastic, sandpaper, and a square.
Step 1: Fabricate the T-Square
- The 3.5" dimension is arbitrary. I feel that it is sufficient, but if you'd like, you can make it longer, to make the T-square more stable.
- The 7/8" width of the small piece is also arbitrary, but works well. It is wide enough to prevent it from wondering too much during glue-up and narrow enough to not be huge.
- Leave a bit of margin for error on each side of the straight-edge part of the T-square. This is because you will be truing it up so that it is perfectly straight and of uniform width, and you'll need some material to work with.
- With your eye, look along the length of the edge.
- Mark the high spot(s) with a marker.
- Clamp the piece to the table and file off some of the high spot(s). Make sure you keep the file square with the T-square.
- Repeat steps 1-3 until you can't determine where the high-spots are.
Similarly, straighten one edge of the small piece. (actually, I was able to use a factory edge of the Plexiglas, so I didn't have to)
I glued up the T-square using epoxy and the jig shown below. Make sure that the edge of the straightedge and the small piece are in contact with the square.
Make sure you clean off the square (using isopropanol [rubbing alcohol]) once the epoxy gets firm.