Hi and welcome to the forum!
There are lots of folks here who also enjoy making their own tools, you'll find lots of help and ideas. I too have a set of Majestic picks, it is one of my favorites because it's an older pick manufacturer that has been around for a long time.
Below is a link to a post I made for someone here who asked about what handles I liked to use. You'll notice that a lot of the handles on the Peterson brand and the KLOM Navigator brand picks are much bigger than the "standard" sized Majestic which are on par with Southord and HPC. I don't notice any loss of feedback, but I have big paws, so I think everyone's experience may vary slightly. I usually think of handles more on the lines of a tuning fork that takes the click of the pins inside the lock and makes them travel down the handle to my hand, so perhaps choice of material is more important than size or shape. Comfort is another big factor, if you're sitting on the couch picking for 2 hours, its never fun to have a pick handle digging into your hand, so I like the Peterson black rubber handles, and the HPC foam sleeves you can buy and slip over normal laminated/riveted handles. So in the end, I wouldn't sweat if the handles are not the exact dimensions as a factory set made by a particular company, make whatever is comfortable for you to hold.
Here are some photos of different brands next to each other: http://www.lockpicking101.com/viewtopic.php?f=8&t=54676
Good luck on your project, share you photos when you are done, you can post them on tinypic.com and paste the http://image.jpg
links on the forum.