It could all be modified, I was heading towards injection molding, but realized that would be a waste of money.
Two things. Milling is expensive, You could easily throw money at this and make it better. Delrin is ridiculously expensive and aluminum block aren’t far behind. My goal was how inexpensive can I make a mill that can mill aluminum at a decent speed, I think I achieved that. Buy buying in bulk I think I’m helping others to get it for a good price as well. The total cost of the parts is less than 2 spools of filament. I use that as my base price right now without looking for a deal thats less than $50 for all the parts.
The second thing is you might be adding significant mass. Adding mass forces you to slow down the machine and you lose power to just moving the machine around.
The reason I like the x and y motor mount out of sheet is to help with the bending and creep that happens from keeping that plastic piece under tension all the time. It is flat because I intended to get this piece cut, I had to add that rib feature because the first one bent too easily.