Hi Mog - Since you may go the path of edge bolting consider plate aluminium. Easy to work with 12, 16 & 20mm are good for edge bolts and then loctite. No need to paint and Al is light and stiff. Where I live there are a few laser plate cutters and they cut up to 25mm steel and 16mm aluminium economically and accurately maybe they are near you too... add a 0.5mm or 1mm edge allowance then machine flat and its good to go. Only mahcine surfaces that need to be flat ie faying surfaces. This will remove the edge kerf from the laser. Good Luck Peter

Its a small world I've helped a guy in Cairo build his router... skype has changed things like that.

I've attached a couple of images from my current build. One shows the bolted aluminium saddle. It's the best saddle I've built, super stiff and accurate. The priors were welded and I had to have them re-machined after welding and I don't think they are as good as the al one. The Al saddle was also used on a bigger machine (Scoot-S3 see attached) and we tested that quite hard and the owner is really happy with the machine.

The "Frankie" machine is made from 16mm plywood and will cut aluminium. My prior machine was bigger and from mdf and its cuts aluminium. The plywood is a test build for a mill. The 16mm ply will become 12mm and 16mm aluminium plate. Its edge screwed and glued together.

Scoot-S3 is made from laser cut, folded & bolted 3mm steel. Its extremely stiff and works great. Again, good Making