Summary I have a situation where the countersunk head of a bolt is hidden and I can't use a screwdriver/allen key to adjust it so I needed to "create" another "head" which I can grip to turn the bolt. I have used two nuts jammed against each other to create the fixed part that can be gripped but to adjust with a finer sensibility I needed something better and larger, hence a thumbwheel. Because the two nuts, when jammed, are not aligning perfectly, I can't use a plastic insert for both nuts so I chose a two-part thumbwheel that are locked together with 3xM3x10mm bolts. This way the bolt can be removed from its setup and serviced/etc. I don't know if anybody else would need this but nevertheless I have uploaded it to thingiverse for reference or convenience.