Used 3/4" thick HDPE that I bought off eBay. Used a circular drill 4.5" hole cutter to make a template out of soft pine wood, then screwed that to the HDPE and cut it out with a jig saw. Used a 5" orbital sander to smooth the edges.
I purchased an old (probably first gen, it looks like it is just a plate that is screwed onto a CG5 hub) Nexstar tripod hub and top plate, unscrewed the plate from the hub. Centered the plate on the HDPE and screwed it on.
Works perfectly. Very solid. Once the horrible midwest weather gets better, I can get it out there and test it out. I haven't weighed the tripod, but it feels pretty light to me.
Edited by Taylor, 23 February 2019 - 04:52 PM.