How to make purse pads:
So you have just purchased or been given a great vintage flute only to find out you have salt spoon keys that are too spherical or have key beds too concave to accept regular flat pads.... time to learn how to make your own purse pads!
Here are a few pictures of the tone holes and original pad of an early Firth and Hall flute that had salt spoon keys. There was no way flat pads would work on this instrument.
The Process:
I use saxophone pad leather to make the pads. It is supple, thin, and easy to work with. It can be purchased from MusicMedic.com. If you have an original pad, place it on the leather to gauge how large a circle you will need to cut. If not, then it is a guessing game from the beginning, which sizing for most of this process is trial and error anyway.
Once your leather is cut out you go to the sewing part of the process. I used linen thread meant for book binding (unwaxed and unbleached). It is thicker than your standard sewing thread, which would be way too thin to use for a project like this. I purchased mine from amazon.com - one order should last you a long time, including tenon re-threading too. I used the wax/cork grease that I make to flatten out the end to make it easier to thread through the needle and tied a double knot at the end of the thread. Be sure to clip off the excess thread after the knot. 
Start your first threading in the leather with the knot facing inward. Make small stiches about a milimeter or two from the edge, but not too small or the thread will cut through the leather. You will know if you have made the stitch too small. Do a few stiches and then push the leather down the thread to cinch it in. Keep stiching and pushing the leather until almost all of the circle is stiched. Leave the last 1/4 of the circle un cinched so that it is easier to stuff. Be sure to leave the threaded needle still hanging on and do not knot the end of your thread yet. It will look like the picture to the left.
I stuffed mine with synthetic quilting batting you can find at any fabric store. Cut out a couple squares about the size of your pad and stuff it in until it is relatively firm. For reference - the D# key on this flute took 4 squares of batting, and the smaller keys took 3 squares. Once the purse is stuffed, then cinch the leather the rest of the way, tie off your thread and clip the end. The end result will look something like this:
This process is completely trial and error when it comes to sizing. Odds are, your first attempt will not be the correct size. When placing the pad in the key, flatten out the top a bit. You want the edge of the pad to come just to the edge of the key at this point and not hang over. Otherwise, the pad will be too large to vent the hole enough when the key is opened. For reference, the following is a pad for the D# key that is too large:
Bringing down the diameter of the initial leather round by about 2 mm made for the perfect size. For this four key flute, I think I made 9 pads total before I got all the sizings right. Below are pictures of the completed pads and how they should look when sized right.
