Bush DAC90.

[pwdrive]

You can use masterboard if it will fit, available in 6 mm thickness, cuts, drills and files dead easy, I have used it as a heat/flame shield when using a blowtorch in tight plumbing operations, also used it as a backing board behind our wood stoves, it comes in big sheets at builders merchants but some diy stores do smaller sheets, off cuts usually available on construction sites, permission permitting.

Lawrence.