I figured with the vast knowledge this forum has to offer I would ask you guys. I Need to fill the in the hole in the rookf left behind when I removed the sunroof from the car Im building to race. I would like to use lexan but I would like to get it to somewhat match the compound curve of the roofline. My idea was to lay the piece of lexan over the sunroof glass I have removed hit it with a heat gun from a distance as to not melt the lexan, but heat it enough to allow it to match the curve. Would this be a good idea or does someone here have a better idea.

yeah, that sounds about right. But be sure to cut the lexan a bit bigger all around before you heat it, because it should shrink a bit.

The theory is right but I suspect that the practicalities might frustrate you. You really need even heating to achieve good results, and I'm not sure how the original roof would hold up to the heat (especially with the localised nature of a heat gun). You might want to get it professionally molded.

I've not tried it with Lexan but when you do it with acrylic you really want to heat the entire thing in one go. If you don't then some bits will be hotter and more flexible than others and it's a pain trying to form it. You'll end up with wrinkly bits and also the possibility of stress marks forming and becoming very visible.

So yeah, if you can afford it then get it professionally done.

Have never done it with Lexan, but generally you would heat both components together until one assumes the shape of the other (given that the mould must be able to stand a higher temperature than the moulding).

Attacking the Lexan with a heat gun is unlikely to work because of the heat distortion point being well over 140 deg C, you would never achieve this uniformally on the piece you are considering, especially as your mould (glass panel) is a very effective heat sink.

The best way I can think off is to find someone with a large enough oven (definately NOT the one in your kitchen ) that will go to at least 200 deg C and heat the Lexan & your sun roof panel together in an oven till you hit the "sagging" point of the Lexan (probably approaching 180 deg C), when it should "sag" and assume the shape of the mould, then allow to cool before seperating. However you may need to provide "force" in the way of a vacuum bag to cause the Lexan to deform, which makes it a bit tricky.

Sounds more and more like a job for the proffessionals but do read the guide here... http://www.bayplastics.co.uk/product%20guide/Altuglas-guidenavbar/prod-altuglass-tech(thermo1).htm

Cheers, Sim