Mr Cult wanted to know how i made this thing & what i used, but i thought i may as well post it here incase anyone else is interested. here is what i can remember:
milling jar -
http://www.stonepolishing.co.uk/ - ?5
nice bog standard tube with caps. needs vanes glued to inside to break things up a bit.
motor -
http://www.mainlineg.../mless/main.php - ?16
I got the "big motor" but thats probably not ideal, although i got it working, i think its a 3phase motor? there are extra wires that i dont know are for. It is slow spinning and high torque tho, hence my unusual gearing. you are probably better off with the "mains motor" and use a different gearing on the belt. (small to big, instread of big to small)
bearings - JJB sports - ?8
come as a pack of 8 for skateboards
go-cart tyre - random guy, sorry lost details. - ?4
i found someone from up north advertinsing tyres for ?4. this rolls nicely, and saves you from having to make ajustable rollers to switch between jar&tyre. However I havent tried rolling comps yet in it, so i dont konw how well it will work, but better than nothing im sure.
belt -
http://rswww.com product id: 475-0232 - ?2.50
pullys -
http://rswww.com id: 350-6286 & 350-6321 - ?2.90 & ?3.80
but you might want to change pulley ratios & belt length etc
other stuff used, you can get from any decent hardware store:
mdf board
M8 nuts & threaded bar (for the rollers. I used a latex/rubber type glue on them for grip)
screws etc
rubber strips & feet (for gripping motor & vibration limiting)
springs
steel wire
hinges
i got that lot from university stores so only cost me ?5 caus they buy in huge bulk. You might have to pay more.
I also made use of some heavy tools, like a lathe, bandsaw and milling machine.
You could probably get away with doing everything by hand except for the lathe. i dont know how you could machine the pulleys without one. I drilled them out and tapped one to fit on the M8 rollers, and used a grub screw to fix the other on the motor spindle. Might be tricky without a nice workshop. Im sure you could find one somewhere.
so adding all together ~= ?47
not too bad i suppose. still a little cheaper than buying one of the same spec. tho this one is more likely to break!