Hi, love the column.....hate the small square table.........a casting will be impractical from the cost point of view.......take note of David DeCaussin's UMC-10 CNC build on UTUBE.

As the man said, castings need to be aged......castings are only really practical if you want to have multiple parts the same without having to fabricate from scratch, but you need to really, as in extremely really, have a design that is completely R&D'd and finalised and not need modifications due to shortsighted thinking......a casting that ends up having to be reworked extensively is a waste of money.

When you go to a casting it's an object that is the final solution and only needs machining where it needs it.....you are going to reinvent the wheel without knowing what road it will ride on?

My opinion is that if you do a fabrication, based upon current CNC technology, you can adapt and "re-invent" it as the need arises without having to outlay for castings which as one offs will not be cost effective for the foundry where the total cost is bourne purely on one item and has to be passed onto the customer.

A fabrication can be re-worked constantly while you re-think the build process as you go along, and it doesn't have to look like a pile of bolted sections like a Meccano set.

By my estimate, you will not get any change out of an "investment" of $50,000 once you add up all the outside manufacturing costs, which will be approx. $50 to $80 an hour.
Ian.