Kenny 1 kilogram is not light! 1kg is 1/12th of a featherweight. If you scale that up to compair with a heavyweight that is 8.33kg which is alot of weight.

Mark. These regulators look good however, can they take liquid without freezing? If they can they will have low flowrate, however this can be overcome with a buffer (and telling your brother to take it easy on the axe).

To me (a bit of an untrained eye but i do know a little) the inline looks to be good. It could be mounted where ever is suitable, i.e. the regulator could be supplied with hp gas via some copper pipe. This copper pipe could also be used as a cooling system in your robot (wrap it around the motors etc).

Thanks for the link mark. These regulators are also quite cheep

Regards
Ian