Summary

I had to measure the middle of a rather large cylinder, so I made these long jaws.
The extensions slide on with a snug fit, and they shouldn't wobble at all. Close the jaws, "zero" them out, and have fun.

On my caliper, I found one jaw to be a 15 degree wedge, but the other (movable) was 16 degrees. So I made mine accordingly. That's why there are two distinct jaw files.

I guess that angle is somewhat variable, depending on how much meat they need to grind away to make a set of jaws perfectly square and flat.

The point is, these jaw extensions may or may not precisely fit your caliper jaws.

They work OK if you're careful. Can't push too hard or something will bend or move. They are far better than nothing, imho.

Metric files provided.

A note about printing with the Afinia. Afinia default settings have a 30 degree support angle.
The interior of the deep hole has a roof with a greater-than 30 degree incline. So, the software won't put any support inside the holes (and there's nothing to remove) if you use the default print settings, and print them on edge, as shown.