A drum carder is an efficient way to card wool to make a batt from which you spin.
I bought a piece of 120 TPI (teeth per inch) 8" x 8" carding cloth from a vendor on etsy.com for about $30. I often spin angora and alpaca, but for recommendations on TPI for other types of fibers, see the comments below.
These supplies cost about $20 from a home improvement store:
(1) 2" PVC pipe (2ft)
(2) 2" PVC end caps
(1) 1/2" threaded rod (3 foot)
(1) 1/4" threaded rod (1 foot)
(9) 1/2" nuts
(6) 1/2" lock washers
(2) 1/4" nuts
(2) 1/4" lock washers
(1) small paint roller
(1) tube silicone adhesive
The "licker in" brush is a "regular" hand carder with maybe 72 TPI that I had on hand.
Step 1: Prepare the Drum
I bought a 2' length of 2" PVC pipe. To cut it to length, measure inside the end caps and mark it on the drum. Don't actually put on the end caps; if you do, you'll have a heck of a time getting them off. : )
Lay the 8" x 8" carding cloth next to that line (making sure that the margins devoid of teeth are on the outsides and not where they would overlap). Mark the length of the other end cap and cut. Drill holes about 1/2" in from the line to aid in sewing the carding cloth to the pipe.
Trim the carding cloth if it overlaps more than 1", but know that a layer of the silicone adhesive will add 1/16" or so in diameter to the pipe. Don't panic if the ends don't meet completely; you can fill in the seam with more silicone later.