In message , Rick Hughes
writes
Simple Q ... you can get plastic balls (ooh er missus) that attach to
shock cord, about 20mm diameter solid items, with a 5mm (or so) hole
thru centre.

such as
http://www.innovativescuba.co.uk/tank-banger-PT106

I don't want to make a tank banger, but I do want to get hold of some
of these balls .... anybody know what they are called ? ... and
importantly where I can get them.

I tried half a dozen outdoor shops today with no luck, but got some
pretty coloured shock cord :-)


google for Ben Wa balls


--
geoff