Always keep in mind that the worst that can happen is that you’ll need to re-make a part. No problem, you made the first one, the second one will be easy.

Here is a list of thoughts about building the organ:-
1. I used balsa and didn't really have any problems. I cut it with a razor saw and steel ruler. A piece of sandpaper taped to a flat surface (I used a 12" marble tile from the home center) is the only way to go for sanding pipes and other small pieces.  I saw some bass wood at a different hobby store after I finished the pipes. If I'd seen it sooner, I might not have used the balsa. I don't know about working qualities, but the bass wood does look better. Coat the inside of the pipes with diluted yellow glue per the instructions. I used chamois leather from a car chamois for the stoppers. I also used little turned dowels for the handles on the stoppers. They look more authentic than a plain bamboo stick. I also looked at the super glue at the hobby store. Have not tried it yet, but it sure would be faster. There is a lot of drying time with twenty pipes.

2. I found some 1/8" cherry at a local woodworking store. I used it for the covers on the pipes. It looks very good.

3. I also covered the front of the 15 smaller pipes with maple veneer (because you can see the glue joints on the front). The veneer looks great with the cherry covers.

4. I used leather for the bellows and reservoir. Glued on with fish glue, excellent stuff. CPL gusset leather and fish glue from Columbia Organ Leather.

5. I used rubber tubing from player piano supply 1/4in and 5/16in, with brass tubing from the hobby store. It looks much better than the clear plastic, and I think it will last longer. Plastic tubing will turn brown and oily eventually. Using brass nipples on each pipe makes it much easier to attach and remove the rubber tubing. I used a small wood block like Ed Gaida shows on his web site.

6. I made the crankshaft by gluing it together with lock-tite and then pinning each joint. Looks good, no lumpy welding. This method is described on this web site.

7. I used 1/4" birch plywood for the box. For the pressure box (and everything else for that matter), make sure everything is as square as possible. On the Universal, I've bought some maple ply with MDF core. Very flat and stable, I think it going to work great, and it looks beautiful.

8. For the take up spool I used two pvc pipe couplers. I made three 3/4" particle board disks. One fits in the center with epoxy to hold the two couplers together. I have a metal lathe so I turned the finished plastic piece down to the right size and trimmed it to length. The other two disks went in the ends. For the flanges, I used two non-silvered blank CDs.  Trimmed them down to the right diameter and sanded them with a random orbit sander to give them a nice cloudy finish. Blending the new with the old!

9. For making the several disk shaped pieces, it's hard to beat a simple fixture on a disk sander. I'll try to describe mine. A square of scrap wood about 10" square by 3/4" with a groove across it 3/4" wide by 3/8" deep.  Clamp the board on the sander table with the groove pointing toward the disk. Then cut a piece of wood about 3/4" by 3/8" by about 18" long. A nice sliding fit in the groove. Drill a hole near one end of the stick for a small pin. It can be a wood dowel, but I use brass so I can turn the diameter to the exact size I need. Rough out the disk to just over size. Put it on the pin and slide the stick into the groove. Clamp a stop block on the stick to control the size. Just slowly turn the disk against the sander until it hits the stop. I added a screw in the end of the stop block for fine adjustments. I've seen similar ideas in several woodworking magazines.