PVC pipe with engraving on inside.

Using the g-code interpreter that I am developing for the g-code splitting program I read some g-code generated by F-Engrave and mapped the coordinates to the inside of a cylinder.  I had a Dremel bit with a small ball at the end (larger than the shank).  So I was able to cut a design into the inside of a cylinder with the tool axis aligned with the pipe axis.

Engraving inside of a PVC pipe.

I thought it was interesting but I have no application for it yet.  I also tried cutting a small lithophane but the results were marginal.  See the photo below.

Mini-Lithophane Attempt