I am going to use 100mm I. D. thick PVC tubing. With tapered end plugs so as to have quick change of the tubes only, in order to accommodate different grits on individual tubes. Abrasive width about 300mm. It will be fitted to a Jet mini, so portability/through-put, not too much of a problem.
Robbo. I read or watched something that suggested that paper onto a solid surface was a bit harsh. Suggesting that the velcro combination would give a slight cushion effect.
Eric, yes I saw that video. Interesting idea and very simple to try, it may be my first port of call. Especially as the example, I believe, was referring to a top slot sander. Another option worth considering perhaps.