Micro-balloons is a brand name for an epoxy filler used in model airplane construction. The material is a white powder made from tiny hollow glas spheres, about the consistancy of flour. It is mixed with epoxy to form a thick paste. The filler makes the epoxy much stonger, more flexible and improves flow. Hardened epoxy can be cut and shaped with wood working tools. There are several brand names for similar materials. Note: Hydrophobic fumed silica (the stuff we call 'dry fly crystals' also makes an excellent filler.

Here are some sources...

http://www.epoxyproducts.com/2_fillers.html
http://www3.towerhobbies.com/cgi-bin...P?I=LXHZ15&P=8

Greg's post showing the blown out reel seat is a good example of 'How NOT to' for masking tape shims. Notice how the 2" wide tape covers the whole entire width of the reel seat, this left very little room for the epoxy paste. I don't see anywhere that the epoxy can bond to both the rod blank and the reel seat. This type of application it prone to fail since it's depending on the inferior adhesive in the masking tape to do the work.

My method only uses the masking tape shims as a temporary 'mold' for casting epoxy/filler bushings. The strength comes from a continious bond of epoxy/filler from rod blank to reel seat. I use 1/2" wide tape leaving at least 3/4" wide spaces between the tape wraps. It's the space between the shims that fills with adhesive paste making a 'cast-in-place' bushing of epoxy/filler. Leaving a 1/4 space at each end insures the tape shims are encapsulated with epoxy for a watertight seal.