Flat vinyl records... Please chip-in to insite!

I tried oven. 
Direct sunlight between 11am and 3pm works best even at lower temperatures.

The old Metal Halide lamps would easily provide this light/heat. These bulbs are for growing and used to cost as much as $500-$1,000 depending on wattage.

MAtt

The oven technique is a little tricky but works. The secret is to find the right temperature and time. A good starting place is 150 degrees F for 5 minutes. It also helps to sandwich the LP between two sheets of glass to ensure the LP comes out flat. Also weight down the top sheet of glass with fishing weights or similar. Nothin’ says lovin’ like something from the oven. 🍪 🍪 🍪 🍪

I have used the Vinyl Flat and have the Furutech (made by Orb). When I first got the Furu, I figured- go the limit 2.5 hours of heat- it did flatten some badly warped records, but caused other problems to crop up. I now adjust the heat duration to more closely match the weight of the record and severity of the warp, with far better results. (Shocker- this is what the manual instructs).
When I was using the Vinyl Flat, I used a gradual, incremental approach- 2.5 hours heat, long cool down. If that didn't do it, I would increase the heat cycle by a 1/2 hour. This worked pretty effectively, but was far more time consuming (admittedly at far lower cost that the Orb/Furutech). 
I have no idea how much heat you'd want from a lamp, CZ. If I recall, Vinyl Flat suggested measuring the temp inside their pouch and considered 140F to be an appropriate temperature. That was in a heating pouch that was velcro sealed around the compression plates.