I was in Error. I thought the weight measurement was Troy ounces, which is 12 ounces to the Troy pound. My son Corrected me, that the Imperial measurement is 16 ounces to the pound. Thus, Jav's should be 1 lb and a half (24 ounces) not 2 lbs which I was misquoting.
I found that by reducing the amount of tape, especially heavier varieties of Duct tape and Double sided duct tape, I reduced my 3 fiberglass pole Jav's to 1lb and a half. (Mechanical mail scale).
I think the 3 fiberglass pole construction (driveway markers from lowes) would work fine and be lighter without gluing the complete 48 " of cores. I think glue and good taping at top, middle and ends, would be sufficient since some flexing of the cores for Javelin's would not be unreasonable.
I made the heads and pommels with Double Sided Duct tape, and quick and easy to work with. It is heavier than DAP.
I used one strip of Double Sided Duct tape on the haft in order to twine blue foam around it for haft padding. I think Carpet tape would work just as well (I tested a piece) and is lighter if not stickier than the DS duct tape.
The heads are 3.5" standard Dag size. I used charcoal open cell (about a 4 " square, taped and cut to a circle, on top of a disc of Yoga mat and then the blue foam for cylinder bodies and caps. I was tempted to experiment with Marine foam, but decided not to. I'm going to save that for my next spear project.
Konradr