Firstly, Jono, 120mm rather than 130mm is no problem, they can do that.
Secondly, they don't attach the caps at all, either welding them or screwing them in. They've said they fit so tightly they don't need any further attachment, they play with them just like that, but you could put in a couple of small screws if you wanted. Sounds interesting...
Ok, I've talked to 3pmh.
Firstly, Jono, 120mm rather than 130mm is no problem, they can do that.
Secondly, they don't attach the caps at all, either welding them or screwing them in. They've said they fit so tightly they don't need any further attachment, they play with them just like that, but you could put in a couple of small screws if you wanted. Sounds interesting...