Rocketpoxy is awesome! I had only made fillets with Titebond M&T or with Bob Smith epoxy before finding Rocketpoxy; there really is no comparison. It's a little pricey, but it is great to work with. It is really thick, so you have to mix it and then spread it out on piece of scrap cardboard or a paper plate. I let it sit for 20-30 min to get rid of bubbles, then I gob it onto the fillet area and, after settling for a few minutes, I shape the fillet with a plastic spoon. (Lots of people use a small piece of PVC, but I think a spoon works way better.) It should make a nice smooth fillet with little or no sanding required.
I show a little bit about how I did my first Rocketpoxy fillets in post #34 of this thread:
www.rocketryforum.com/showthread.php?130...annosaur-Build/page2