In the uk. This sort of thing:
[img] 
[/img]
I know I could fashion something out of an old coke bottle and some valves, but the above seem relatively cheap in the states etc. and I'd assume a bit less explosion-prone. Can't find one for sale in the Uk though.
For seating tubeless tyres, if it wasn't obvious...
[url= http://www.google.co.uk/products/catalog?q=air+receiver&hl=en&prmd=imvns&psj=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1280&bih=608&um=1&ie=UTF-8&tbm=shop&cid=6840338028741122885&sa=X&ei=vlSET_KRCsnL8QOOhuDCBw&ved=0CH8Q8wIwAA ]Air Receiver[/url]
[url= http://www.ebay.co.uk/itm/Air-Compressor-Tank-/280859530326?pt=UK_Air_Tools_and_Compressors&hash=item4164885456 ]Ebay[/url]
[url= http://www.ebay.co.uk/itm/compressed-air-tank-cylender-50-litre-/160779158093?pt=UK_Air_Tools_and_Compressors&hash=item256f2f424d ]Ebay[/url]
Hmm, 1st one quite pricey, bigger than the small ones I've seen I think.
2nd pick up only, not sure about an old pressure vessel, possible rust/leak issues.
3rd also big, collection only again...
I [i]did[/i] actually look in the obvious (to me) places, but maybe someone has a better idea.
old fire extinguisher and go speak to the nice man at your local compressor/airtools shop
Just went up market ghetto!
http://www.ebay.co.uk/itm/251021739447?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648#ht_1534wt_952
Plenty at Matt savage, dunno if they are what your looking for though
http://www.mattsavage.com/acatalog/Tanks.html
I've got some diving cylinders I could sell you for a decent price, collect in Leeds?
I may go up market ghetto - what pressure does that hold, not sure I'd risk more than 40-50 in it before getting scared? Enough to seat a tyre?
Leeds is a bit of a mission I'm afraid.
What are you intending to pressurise it with?
It'll take a while with a track pump, I'd have thought.
How about using a 5m long 1/2" hose as your reciever? You'd need a stop valve on one end with a line to your tyre valve, and your track pump connected to the other end.
Not sure home much pressure ghetto will take but it does have a pressure release safety valve. I'll see how many pumps of the handle it takes to pop out and work back from there.
I can't see why someone hasn't worked out a way of doing it with mains water pressure.
Hose might work, but is only about 1.5 x the volume of a 29er tyre, with some rough maths.
Well, if it has a safety valve, it must be safe. Sorted 😉
Does it work well for you? Volume wise it's about 2 tyres, so should provide a good flow to seat a tyre I'd think?
It's more than likely you own something suitable already. You don't really need that much pressure to seat a tyre, just lots of volume so a car tyre at about 35-40psi works perfectly.
I don't use a hose, its just a thought. If the calcs don't work out with 5m, use 10m, or 3/4" hose.
It'll be a balance between pumping for too long and not getting a tyre to seat. Probably best to have 1.5 tyre's worth of air in your reciever, though. You won't want to pressurise a 2 tyre reciever, when you come to just seat one tyre.