I did something similar on one of my other cars, i used a bit of ARB (All round band) comes in rolls from 3 mtr upto 25 mtrs in the big trade packs, its available from most decent electrical wholesalers and plumbers merchants they do it plastic coated and bare and even in different size holes.
All it is a strip of metal about 12mm wide with a hole drilled in it every 20mm or so, just wrap it round the neck of the filter and fasten back to any available stud or bolt, prior to getting hold of this (nicking from work

) i used a bit of metal strapping from the hardware aisle at B&Q and just bent it to suit an existing stud from the previous airbox and used a couple of heavy duty cable ties to hold the filter to the bracket.
Hope this helps.
Erm P.S just read wellys comment and we are talking about the same stuff

, so u could call it ladder strap or u could call it ARB, but its the same stuff and available from just about everywhere the trades shop. a google search tells me ARB about 8-9 quid for 10mtrs online.