Vinyl cutter tool holders are similar, have adjustment for pressure are easily modified best of all available for just a few pounds on eBay. I watched a guy engraving wine glasses on a 4 axis with a diamond tipped bit apparently engravers have been using them for years. Have not tried it yet my vinyl cutter is in the back of my lock up with the toolholders etc. Just have a look at the Roland toolholder knock offs from china etc they tend to be alloy so will have limitations but for fine work look ideal.