1. I made a plywood template; one edge matches the stock roofs lengthwise crown, the other follows the lateral crown . 2. and took it to a local junkyard to shop for a matching donor roof ~74 x 43 with no lengthwise ribs. I was looking for a Volvo station wagon but found an 86 Toyota minivan matched perfectly. 3. A battery-powered sawzall got me a new roof and three interior reinforcing crossmembers, one of which contained a dome light and wiring. Thanks to my buddies who loaned me the sawzall and helped with the roof-lobotomy. 4. There are two ways to weld the insert: You can either lap-weld the insert over the stock hole, leaving the stock lip where the wood slats used to rest. Or you can remove the lip and butt-weld the insert. Since I was using a MIG welder, I chose the former, because (a) theres no gap between the patch and roof for the welder to blow through, (b) vinyl will cover the seam anyway, and (c) the lips rigidity helps minimize warpage, which was a huge concern. 5. I applied Dykem, then measured and marked scribe lines and cut it with a jigsaw and new blades. The patch overlaps the stock sheetmetal hole by 0.25 on all sides. 6. Then I sanded both the patch and roof down to bare shiny metal and sprayed the edges with weld-thru primer. 7. Tack, check, pound, grind, repeat All welding was done with my small but trusty Lincoln 140C with Argon/Co2 mix and ESAB easy-grind 0.025 wire. 8. The long weld seams shrank a lot. I minimized it with short tacks and moved around to prevent heat buildup, but the shrinkage around the patchs perimeter raising a noticeable bubble above and between the rear windows. 9. I alternated between ~20 minutes of tack welding, followed by ~three hours of hammering on-dolly around the perimeter to stretch it and drawing down the bubble with a shrinking disc, then checking my progress with the plywood template and repeating the tack weld/hammering/shrinking process. Also, the roofs extremely low crown (its almost flat) would cause it to oil-can if not for the shrinking disc and the Toyota minivan crossmembers.