Hello guys, this is the situation:
I need to use them at 120-140°, and I also need to make them at the first try, to minimize the costs, the time is not a problem.
what do you think is the best way? epoxy putty? or maybe infusion? I think that the second choice is the best, but I’m open at any suggestion.
Which resin to use? remember that i need to buy just a small quantity.
thank you guys 
Why do you need mirror covers that can take 140 degrees?
Honestly I think that if you needed tooling to go that high then the best solution would be pre-preg or aluminium. Any infusion resin that can take that heat is certainly not going to be cheap. But then neither are the materials you would need to make a pre-preg or ali tool (tooling block or ali block).
Realistically I think if you have a low budget then you’re not going to get there. If cost is an issue and time is not, then I would suggest simply using a vinyl ester tooling system and pushing it’s capabilities. You will drastically reduce your tool life, and you may lose your surface finish and need to do a bit extra polishing, but it will be cheaper materials wise. Of course if you need to make 200 of these things then it would be cheaper in the long run to invest in proper high temp tooling, but if you’re only making 5 of them then just stick to conventional methods.
tecnique is resin film infusion, so I need 120-140°, with my usual vinyl ester process it was ok, but the problem is that those resins comes in 20kg tanks, I can’t waste them, so I will need a large ammount of models for mould making, so a really higher initial budget. the project is to start a 10 couples production for restarting the activity.
I’ll probably go with epoxy/fiberglass mould hand layup, but please, let me know if you know a really good commercial grade vinyl ester resin
other than Tg of resin, you might want to consider possibly issues from CTE differences of mould to part. Are the covers Carbon? If so, you might find some interesting issues curing at that high of temperature. Usually the solution involves demoulding hot, which is not usually fun.