This adjustable doohickey allows you to quickly add seam allowance to sewing patterns. You can change it to use whatever width you are using using the screw on the side. It uses M3 hardware.
This is just my first go, I think I want to add a second wheel for stability and some kind of pensioner for the pen insert.
requires M3 bolts, nuts and the insert from a pen (e.g. biro)