The Boom Arm hose from Festool is , if I remember right, 50mm diameter, and not that long. You would connect a 27mm regular sanding hose to it, or a 36mm hose if chips are being collected more than Dust. So, Festool thought it was a good idea to have a larger suction hose off the Vacuum/Extractor going up to the boom arm, before you attach the other tool hose. You might be able to reproduce your own if you don't want to buy theirs, but make sure what ever fittings you use connect the input hose end into the vacuum inlet easily, and the same easy connection at the other end of the boom hose for accepting the tool hose. Basically 50mm male into the Vac, and 50mm Female to accept the Sanding or Cutting Tool Hose.
Maybe do a search here on FOG as I would think someone else has run into this before with a Homemade Boom Arm.
I actually use the Festool Anti-Static Boom Hose to connect a Vacuum to my Oneida Cyclone/Dust Deputy, since it allows me to put a systainer or Sortainer between the Cyclone Box/UDD or just put the UDD directly on top of the Vacuum.
Okay, I did the search since I thought, this should be easy, we've covered this topic before.... hah, anyway, the stock AS Boom Arm Hose is 50mm by 1.5 meters, or about 5 feet long. You then connect your tool hose to that. There are posts on making your own, or buying one from Oneida instead. A good Festool Dealer should be able to get the actual, fully assembled 50mm Boom Arm hose part number for you, as I don't remember buying the short hose and both rotating 50mm fittings as a kit, mine came fully assembled, but not cheap.
