A while ago, I made a set of bellows which I documented here: http://www.freewebs.com/stevesmithphoto/bellows.html
Whilst they turned out o.k. they were not quite what I had planned. I have recently made a new set which fit my new camera better so if anyone wants a set of home made bellows for experimenting with, they are available for the cost of postage.
Rear 165mm square, front 90mm square with an internal dimension (just) big enough for 5x4.