Not entirely from scratch. I had a thread dedicated to the build, but it got nuked by Reks.
I purchased a VPI Aries special edition Black acrylic platter, about 2" thick, along with the accompanying inverted platter bearing. Then purchased a Rega RB300 tonearm with upgraded Cardas wiring. Then outfitted that tonearm with Pete Riggle's counter weight and VTA mechanism.
The plinth I built was rather complex, with 6 alternating layers of 3/4" birch plywood and 3/4" MDF. I drilled a series of 10 holes about 1 1/2" in diameter and 3" deep, on the bottom of the plinth. Those I filled with the modern version of lead shot, for even more anti resonate properties, and made removable caps, so that I could adjust fill levels accordingly. I wrapped the plinth core with 3/4" Walnut, Walnut corner posts and Big leaf Maple burl veneer on top. I made the tonearm board out of Walnut, and made it adjustable by about 1/2". Marc built me a Pass Pearl phono stage and also a DIY motor controller, for the separate motor pod and Maxon motor.
The turntable weighs in at around 75 lbs. And it's enormous! Hence the name Colossus.