To be able to melt metal stuff you need to find at least 5 red beam upgrades. There are 6 total. All their locations in this video guide.

All Red Gun Beam Upgrades

Timestamps

First of all, the game is really deserves to play it through with no guides, but if you really getting mad and cant find some upgrades, here’s the guide.

00:05 >> Gun Altfire Damage Upgrade #1
01:39 >> Gun Altfire Damage Upgrade #2
02:16 >> Gun Altfire Damage Upgrade #3
02:41 >> Gun Altfire Damage Upgrade #4
03:20 >> Gun Altfire Damage Upgrade #5
03:42 >> Gun Altfire Damage Upgrade #6