Corner guages (fillets and radii/radiuses)

thingiverse

Measuring dimensions with a digital caliper is great - until you get to something with rounded corners. How round are the corners? In the past I've just guessed, and got it very wrong. Lots of iterations to get it right. Why didn't I think of this sooner?! A set of "cards" like feeler guages, where you just try each one until you get a snug fit, so quick and easy. There's two sets, one for measuring internals, one for measuring externals. Both go in 1mm increments from 3mm to 12mm. That covers most small things round the house like sockets and things. I might do a set for bigger corners at some point. Each "card" is 15mm x 30mm, with a 5mm hole for connecting them together via keyring, string or wire etc. I like using the 12cm wire loops that are often used on luggage tags, you can pick them up very cheaply, I got 20 for 4 GBP. They're so small you can easily put them in your pocket.