Awhile ago I added a shuttle race extension onto my Macomber:
As I was using it, I kept thinking that it was about half of what I needed to make it into a fly shuttle. So I did that over the weekend. Here is an overview picture
You can't see the top, but it's attached to one of the top railings of the warping trapeeze that I make awhile ago. (http://weavolution.com/group/home-built-equipment/diy-warping-trapeze-19615)
The shuttle in it is a Schacht end feed shuttle. I've tried the Buster Bay in it also, but that doesn't work as well since the shuttle itself is not carved symetrically, but bends to one side. Here is the shuttlel box:
And here is a better picture of the "pusher." Notice that it's made to push the shuttle into the reed. This keeps it from flying off at the other side.
And, because I like to use a floating selvage, I added a chord behind the reed to do that, using the idea that BigWhiteSoftDog posted awhile ago.
You can see the chord raising the floating shuttle from behind the reed. It works amazing well! BTW, that piece of white behind the shuttle is a piece of cardboard I put in on each side of the reed because the reed that I'm currently using, while wide enough for this warp, is too narrow for the loom. I was afraid the shuttle might sail into the shaft! I haven't stained the wood to match yet - I wanted to first see if it worked.
There is a little brass "fin" that helps guide the shuttle into the box. Because of the railings that the pusher rides on, once the shuttle starts into the box, it's not coming out!
I'm still learning exactly how to jerk the chord to get it to work smoothly and to get my weaving rhythm down while using it, but that is my learning curve. The contraption seems to work very well.