How about a mycncuk cnc router project?

[JAZZCNC]

Materials to cut - should include Plastics,MDF plywood, hardwood, PCB material and aluminium (Ithink that probably rules out MDF construction).

Here comes the "Horses for courses".!! My experience shows me the best most successful machines are the ones optimised for one main purpose. At 1K working with spindle Etc then cutting Aluminium with any serious intent and surviving the experience can't be done successfully. Best kept to Woods, plastics, PCB, Composites etc.

Size - typical working area should be to optimise standard sheet (8'x4') use, so something like 300x400, 400x600 or 600x800

Agree on sheet sizing and 8th sheet would be the optimal for desktop machine under 1K. So 650x650mm.

Desktop or floor standing - Desktop is perhaps prefered by most diyers due to space availability.

If we want space saving how about Vertical.?

Another parameter to discuss -frame materials - steel/ally, sections or extrusions. G

I'll say straight away that I'm taking NO further part in the discussion if MDF becomes part of the design other than for a Sacrificial Bed.!!

Size and budget will mostly determine Material used. Extrusion is expensive with the main reason for using being ease of use and this often needs expensive fasteners which will make 1K target harder to achieve.
Steel box section is far cheaper but requires more tools and for ease of use welding helps greatly but up's the skill level slightly (it isn't difficult at this level)