BEagel why don't you go into production? Or point an FI in the direction of some extra cash.
Local fabricators with a flow cutter and get them to cut out 10 or more rounded rectangles of your design (more you do the cheaper it is). Remembering a couple of slots for some manly elastic.
If you really want to go for it get them to cut and bend some plate to form a surface for your thigh with the elastic holes in it instead.
Rivet the thigh bit on underneith.
Rivet a suitable clip to the top of it.
Using the handel of a McFLurry spoon, cut the spoon off then glue the handel to the top or underneith what ever takes your fancy, left or right handed versions are dead easy. Thats your pen holder if you want more pens eat more ice cream.
Then ask a girl whats the best way of attaching the elastic.
Depending what buckles etc you use with the strap I can't see it costing more than 35 quid.
Metal 10 quid
Flow jet and bending 15 quid each.
Rivets, clip etc 5 quid
McFlurry 1.50 (the ice cream is a bonus)
Elastic velcro etc 5 quid.
If you use hillwalking quick releases instead of velcro maybe 35-40. And its got to be better than the 20-40 quid plastic jobs which fall to pieces after 6 months.
Then flog them in the club or on ebay for 50 quid or paint them mat green and flog them for 60 quid (you could do a special pink one for a certain person.). I sould imagine there might be quite a market for them especially as they might help rotary pilots as well.
If you don't want to do it and there is PPL out thier that owns a Fabrication shop I will be quite happy to knock some drawings up for 2 quid to the Poppy appeal per unit. There is also a need for just a plain AL A4 board with a clip on the top for IR work.