I have had the need to just cut a circle or square out quickly. So I have been slowly building a library of primitives. In Inkscape I draw a square, circle, oval, rectangle or polygon and just save that by itself properly labeled. My design and labeling is in mm.
So tonight I needed a 3/4 inch right triangle to prop something up. I just open the 50mm right triangle, zoomed in on the GFUI and resized it to .75" using the rulers. Then Lasers! It’s quick and easy primitives until we can start to draw inside the GFUI.