I've found this hole cutter

[The3rd Earl Of Derby]

To be very helpful when cutting holes under 120mm in perspex/tin/alluminium.

Just arrived this morning. :-)

[John Rumm]

of a soil pipe with one for fitting a strap on boss.

[The3rd Earl Of Derby]

Dunno about that, I did use it in a drill press on flat perspex.

[Staffbull]

Screwfix do one as well, got one last year to cut holes for recessed

12v halogens in the bathroom.

[Fred]

used when the main cutter comes into contact with the material so the central hole shouldn't enlarge the hole like this one once cutting starts.

[The3rd Earl Of Derby]

50GBP, blow that for a game of soldiers.

[john2]

I had one 15 years ago, but found it to be suicidal to use with a hand drill due to the cutter digging in and stalling. Might be OK on soft plastic in a bench drill.

john2