Hello Martin.

I've kept an eye on this site Aluminium Supplier | Aluminium Stock | Aluminium Warehouse for the EcoCast plate, as Jonathan says its premachined on both sides, looks like a good option. No doubt other folks will comment if its not. I costed a 20mm thick plate using the EcoCast of approx 450X200 one off for just under 40 GBP before VAT and Shipping. I havent gone ahead yet so cant confirm shipping. From what I've read here Alu plate is desirable becuase it is easier than steel to machine. So for those with an existing machine that can cut Alu, a good option. I do wonder what a comparable size steel plate would need to be for the same rigidity, I'm assuming 1/3 the thickness due to a comment I read somewhere about material density? As I dont have a machine already I'm not planning to rebate the Z Axis rails etc so I might just go for 7 or 8mm thick steel, but like yourself, I'm still reviewing options.