I like your design so far. We built a couple of Kossel Deltas, we printed all of our own plastic parts and sourced out the hardware to various vendors. Both have heated build platforms and both print very well. We have pony printed PLA on these machines because they are open framed and we already have six different closed frame printers for ABS.

Of course, the downside on the Kossel is the Power Supplies do not fit under the machine. We also have our Ramps Boards mounted on the outside of the frames so we can have active cooling although I have seen some Deltas with the boards mounted under the Build Platform