This is a set of arched squares.  

I designed these because there is often an obstruction, like a fillet or some hardware, at the joint between two parts that you would like to square up.  

There are two variants, Plain or Fancy.  They are the same outline but the Fancy version has a fractal grillwork which takes longer to print.

There is also a box to hold the set.  You will need to cut some 1 mm thick acrylic sheet for the front and back of the box.  I used a plastic cutter to scribe and snap the sheet and then sanded the edges to get a good fit.  Glue down the back side.

I printed these in PetG on a Mk3.  Project files for the Prusa Slicer are included as well as STLs and gcode.  Source files for OpenSCAD are also included.  Be aware that the Fancy version takes a long time to render (several minutes).

The squares use 3 perimeters, 3 top and bottom, zero infill.  That should make a solid print.

For the box use 3 perimeters, 3 top, 0 bottom, 20% honeycomb infill.  That will make a honeycomb layer on the bottom which helps prevent warping.

If you are using OpenSCAD, do yourself a huge favor and get one of the more recent releases.   I am using 2024.03.28.  Go to Edit | Preferences | Features and check the boxes for fast-csg and manifold.  This will speed up previews (fast-csg) and make the rendering use more than a single core of your computer (manifold).  For me this improved rendering times by more than 100x compared to the older version 2021.01.x