Edit: Update: Today mail and UPS grought some thin M5 nuts and 8mm steel rods & linear bearings!
Looks like I can start putting the frame together today after all!
One would not think that one of the most difficult parts to find could be M5 screws.
With help from local fastener store (Kärkikiinnike in Vantaa, go there if you need some not-so-usual fasteners) I finally got box full of hex-socket head M5-10mm screws. Just a small box, 500 of them. I will have something like 400 pieces left over after this thingamajig is ready.
Even more difficult to find are the t-nuts (or square nuts, they work too). Looks like I have to order them from China or from USA (Made in China too).
While waiting for the rest of the parts to arrive, I did some tapping.
Tapping threads to aluminium profile is easy. All you need is battery operated drill (= more torque), some WD-40 or CRC 5-56 and some time.
Profiles tapped. Now if I just could find those t-nuts I could start building the frame...
Overall status of the project:
Blind joint screws
Belts & pulleys
Aluminium extrusions (profiles)
Z shaft couplers
8mm thrust bearings (will take stress away from Z-axis motors)
T-nuts or square nuts
Heat proof spacers
Power supply (12V,30A)
Arduino Mega2560 (Ordered from eBay)
And that's it for now.