[Bob Carriere]

Ducting sold by wood working shops for dust collectors....comes in various size but would need painting as it is usually transparent to detect blockages.

Princess Auto also has a similar pipe for sump pumps....wire coil is designed to keep piping from collapsing under vacuum.... also clear plastic but could be roughened up in the blasting cabinet to better hold OD paint.

Last would be a junk yard looking for duct work under the dash of older cars..

Cheers