Just popped on to post a couple of files I did recently. Both are very simple, and 3D printed without any problem.
The first is a centre finder. I had a large one, but wanted a smaller one for ease of use on small pieces of wood. It was designed in TC 2018, and 3D printed using PLA. Note, no allowance has been made for pencil point thickness. What I do is draw 3 or four lines from different corners of a squarish block, or different points on a roundish block (like a tree branch). ready for woordurning.
The second... I needed to sand narrow edges of some small 3D printed objects, between 2mm and 5mm thick. I wanted to try ensure the edges were still 90 degrees after sanding (My hands are not a steady as they used to be). So I designed a little sanding block. The two printed blocks are pushed together. The tapers force the sandpaper against the ridges, locking a small piece of sandpaper in place. 3D printed using a modified PLA filament (which gives it greater strength and durability similar to ABS, than sandard pla).
Just posting in case anyone finds them useful. Or just wants to see that some things drawn in TC, can be very simple as well as useful.. Both TC files are version 2018 pro, and 2017 deluxe.