Kingcreaky, thanks for the help and the PM!

Martin, I know it's hydraulic but since it's all contained in one unit I don't have to work out what to get in the way of pumps, hoses etc :-) To be honest I don't know how much control is necessary to get perfect results but I'm sure that I can get useable results from quite a wide range, I've seen what I want to do done with a sublimation clamp even though the proper pressure is far higher. At any rate I'm generally pretty good at teasing out more performance from something than it's intended to give and if it doesn't work out then I end up with a very useful bit of kit anyway :-)

BTW, the problem may be solved! :-)