4 more portable
the measurements are spot on obviously you'd have to make it a 3 foot circumfrance
many people use modded bum boards / sledges
as balf said one strap and a handle for adjustments
not too expensive probably no more than 30 quid ... as a push preferably 20
you could sell them at the masters to the lads that are reffing there
maybe take orders to put some sort of design on them?