A while back I was thinking about buying a dust collector, after my Sears shop vac went through it's umpteenth filter, hoping that I could lessen the load on that poor old beastie (as well as the noise load on my ears). Being the cheap SOB that I am I decided that I could put together a passable system using an old Sears leaf blower that was sitting unused to power it. The leaf blower seemed to have enough power to move a reasonable amount of air so I gave it a try. I've since toasted that leaf blower (after running it for far too long without a break), but that was my fault because I had taped over the ventilation slots in the motor to increase suction. In any case I've replaced the Sears leaf blower with a Toro Super BlowerVac that was about $50 at HD, and it works much better.
I bought a fiber drum from a local paper tube manufacturer for a couple of bucks. They get their glue in these drums, which are lined with plastic bags, so the inside of the drum was perfectly clean once I removed the bag. The top of the drum did have quite a bit of glue on it, but it turned out to be water soluble and came off very easily, leaving me with a pristine drum and clamp-on lid, which I turned into my DC system.
I cut 2 holes in the top, one in the center, and one towards the edge of the top. The center hole is capped with 2 3/4" pieces of plywood, glued and screwed from the bottom of the cover, and has a hole in it just slightly larger in diameter than the vacuum tube which comes with the blower. I only use the first half of the 2 piece vacuum tube, which extends approximately 1/3 of the way to the bottom of the drum. The inside of the hole is lined with some 1/4"x2" stick on foam type weather stripping to make an air tight fit when the blower is installed.
The hole towards the edge of the cover is just large enough for a piece of 3" male threaded PVC pipe coupler to fit through. A matching female piece fits on top, and when tightened down clamps the pieces together with the cover tightly in the middle. On the inside of the cover, attached to the male coupler, is a 90 degree elbow, turned so that the air entering the drum is directed radially, around the vacuum tube. This allows the large pieces to swirl around the sides of the drum and fall to the bottom, while the air and small dust is sucked through the blower and into the blower bag.
As you can see in the first picture I simply used the bag which came with the blower vac. This bag is not great as far as filtering the very small particles of dust, but since I really only use the DC on my jointer and planer, neither of which generates much in the way of small dust particles, it's not really a problem. Were I to hook this up to a sander for any length of time I'd probably want to install a .5 micron bag, otherwise I'd fill the shop with fine dust pretty quickly.
For a jointer and a planer this DC system works very well. I don't have any permanent piping installed in the shop, as my J&P are fairly close together in the shop, so I simply use a 10' length of flex piping, and connect it to whichever machine I'm using. I think that the Toro motor probably wouldn't pull its weight if attached to a permanent system, and if I ever get to the point of wanting to install one I'll replace the leaf blower with a real DC blower, but I'll probably keep the drum as a first stage, it seems to work well, especially considering it cost me a grand total of $10 for the drum and PVC connections...
So, if you've got a leaf blower hanging around, and you want to build a DC, or are looking for a first stage for your single stage DC, try this out. It's worked well for me.