This is a small roller I made to help with my wife's sewing. It can also be used for rolling the edges of wallpaper or anything you need to roll flat.
The roller diameter is 20mm and 25mm wide. Overall length when assembled approximately 180mm (7 inches)
The roller internal hole diameter is 5mm, the holes in the handle are slightly smaller to allow a bolt to thread into the plastic. A 5mm x 40mm bolt with nut should fit fine but two smaller bolts 10-15mm) without nuts can be fitted at each end instead if that makes it easier to source.