I had an extra Tau Zero (BC-760) nose cone and this is the design that I came up with.
I wanted it to transition up to a larger BT that would be long and shallow. To do this I used a short BT-20 (1.25", just long enough for the two shoulders) to a Semroc TA-2050B balsa transition then a 2.5" paper shroud to a 2.25" BT-55, this is the separation point. Then a full 18" BT-55 with a boat tail. The boat tail is from a Estes PNC-55BB that I had cut the forward part off for another project. This made a perfect boat tail from BT-55 to a BT-50.
I had a hard time coming up with a paint scheme for this one. The "brown" is really Krylon Pumpkin Orange, but because it was painted over silver it changed the color. I expected it to change the color some but not quite this much, but I kind of like the way it turned out. All the black is vinyl except the nose tip which was hand painted.