I’ve been wanting to make a T-Square so that I can resize the sheets of chemcast that I have. I’ve been using my framing square, but it isn’t quite long enough for the acrylic I have. [Right Click and download. The image is an SVG.] [Edit: fixed the numbers. Hard to think through the reverse.]
And metric for the enlightened folks on the forum by popular request. Thanks to @dan_berry whose OpenScad makes perfect tick marks! [Edited: long arm numbers now in reverse as that is meant to be printed on back and laid over top cross bar.]
I used CA glue for the assembly. We’ll see how it holds. I haven’t gotten solvent glue yet nor made my own. The yellow square is an engraving so that the perpendicular arm slots in. Very nice and exact fit with no wiggle just as is. The perpendicular arm is printed on the back so that the numbers and ticks lie on the surface and avoids paralax. The horizontal beam is on the surface as that will be flush to the surface.
An additional image of bed placement. This is a good file to understand the limits of the useable area for cutting versus engraving. The cutting will work and the engraving will work, but you have to make sure that the image of the long arm is placed correctly so the engraving part doesn’t go into the no go zone for engraving. I think I have it positioned accurately on the artboard. If the engraving of the long arm is not getting highlighted, nudge it over. It should fit.
Edit: Note that there is a box around the center engraving on the cross member. That is supposed to be scored, not cut. That is to clean up the edge of the engraving for a good 90 degree glue up of the long leg.