I found this nice PDF (see attached at bottom titled RollerFurler.PDF) a few years back.
I also have some pics in my files. I don't remember where I found these pics. They may be the same ones you already looked at but here is what I have.
If I am remembering correctly, the drum was made from an electric wire spool that was obtained by asking a Lowe's associate if they could have one of the empty spools.
If you want something simpler and also helpful for the solo sailor, ... do you have a down haul on your jib?
Here are two ways to rig a down haul. I like the second way and have used it extensively. If you leave the working jib sheet taught while pulling the sail down, the sail will accorion fold on the deck and lay along side the cabin and not flap in the wind. Then you can take your time reefing the main, or changing head sails.