Small CNC for guitar inlay work - general thoughts

[Washout]

Hi and welcome.

I'll add some thoughts:

If you are "only" looking to cut inlays (and I assume the corresponding pockets) then you don't need a massive machine for this kind of work and this may be one of the rare use cases for the cheap 6040 machines (I think there's is also a 3020). You will have to be "honest" with yourself, as hogging out guitar bodies and necks (whilst it can be done) won't be a quick or easy experience on the cheap machines and a self build route would be better in that case, and there are a bunch of build threads on here you can look to for inspiration/guidance.

Things to look for on the 6040 style machines:

I haven't looked for a while but round supported rails is a minimum and if they are doing linear guide rails go for those instead. Do not buy a machine with unsupported round rails.
Look for a machine with a water cooled spindle, rather than air or one you can upgrade to a water cooled spindle - they are much quieter.
Be prepared to upgrade the cabling and control board, drivers etc. this is one area the costs are kept down and especially when it comes to grounding/shielding and where problems usually occur.
Also be prepared to have to do a bit of maintenance to get everything aligned and travelling smoothly.
Unless you can ensure the seller is providing a "proper" licence of MACH3, be prepared to spend extra getting that also (or go Linux if you are OK with software and running that OS).

Hope that helps and I'm sure others will chime in with other advice (you'll likely be goaded into to building a machine weighing 6 tonnes and built from granite ;) ).

Cheers

Chris