T-Square for Logan Adapt-A-Rule
I bought a Logan Adapt-A-Rule for cutting frame mats/mounts for photos and wanted to add a square edge to it.
This clamps on in a similar way to the matt cutters and provides a right angle edge (if your printer is square). Use two #4x12mm countersunk screws to attach the clamp.
https://www.logangraphic.com/products/straight-edges/524-adapt-a-rule-24_p_56.php