Bit more progress, I've machined the base square and added holes for uprights and underneath supports. I'm still waiting for CNC mill time at work to skim the top and bottom of the base plate.

 The extruder has had a bit of work, the rollers I had setup with a heavy spring to provide gripping force onto the filament, I've done tests and found it to only hold a force of around 40N, so have added two SMC single action cylinders to push directly onto the roller shaft that provides force onto the filament. This gives considerably more force, which is adjustable by adjusting the pressure available to the cylinders, and will make changing the filament much easier as I can release pressure off it. I'll do more tests and hopefully this setup will provide enough clamping force.

Extruder showing SMC cylinders added to provide force onto feed rollers.

Machine base, bed, upright supports machined.

Extruder setup showing brass 0.5 nozzle and machined teflon liner.

Extruder, awaiting drive pulleys and belt.