Gearbox - ripping the top off

[JCJC]

First time out yesterday with a secondhand D4, managed to catch something, must have pushed the front shock tower back, ripped the top of the gearbox off, new parts £11ish

Wondering how common this is going to be and if there are any quick and simple solutions to make this a bit stronger. Not a difficult part to change - but an £11ish shock tower would have been easier. Any thoughts ?

What other parts are good to keep in the kitbox.