[vacpress]

im not an expert - but i really doubt a sinlge resin-cast part used as the base for a CNC machine is a good idea.... there are a few reasons i think.. the main one is cost vs performance compared to other materials.. te other is my belief that poured liquid resin plastics are not dimensionaly stable over time, or in different environments. I think a big casting made of that material would have all kinds of problems with sinks, uneven walls, etc. and then it would all shrink and warp... another similar, probably not that usefull material could be fiberglass enforced bondo... Still. i doubt bondo would make a dimensionally stable base..

i would imagine even MDF would make a more stable base than an epoxy casting, but aluminum would be far better, and maybe even cost a similar amount of $$ - assuming you have the equipment to work with it... but casting alrge resin parts also requires equipment... a vacuum setup is pretty vital, and so is a digital scale.. i have done lots of small castings, in lots of materials... so i do speak from some experience...

concreete is an idea.. possibly as a base slab... make a precision gig that lets you sink hardware into the wet casting, so you can bolt other parts on... that may be cost effective compared to using an all metal base... and also nice and stable... molds maybe could be produced with expanded foam...

i think i have heard of other, more appropriate resin-type plastics, but i bet they cost alot of $$
ideas?