Seems always to be requests for 'em Tony.
Not hard to make, easy to store. Heck, don't put a bend in em 'till ya send em out and even easier to store. (depending on how ya make them) And would be doing the community good.
For any one who has never tried one. They are great. A bicycle is set up so that your weight is over the pedals so as to give ya more umph and make it easier to press down on em. When cruising with a motor or engine, there is no need. So you're in a less comfortable, prone position leaning on your arms more than necessary. With a lay back seat post, your feet are positioned further out in front of you and your weight is on your butt. Far less fatiguing, too. As vibrations being transmitted up your arms and using energy holding yourself propped.
But rather, scooted back on yer arss like Good intended. LOL
Seriously, do 4 hrs on an uncomfortable, lil vibrating 2 smoke and same 4 hrs on one with a layback seatpost. 2 different days.