I had a toy as a kid that was a ball launcher made out of a towel with sticks put in pockets on both short sides. Put the ball in the middle, hold the sticks and bring your hands together. Snap your arms out ward to shoot the ball up high. I haven't whiped one up (waiting for free time) so I'm not sure about height, but I do remember that it gives acuate vertical lift with a little practice. So it may not increase height compared to throwing but it may improve accuacy. Less time throwing more time climbing. I'll work on this. pics later.

a standard hunting slingshot, and a spool of Berkley FIRELINE, 50lb test, and several 1 oz fishing wieghts.

the FIRELINE is so slick and tough, that the little 1oz lead weight will punch thru a heavy canopy and return to ground in seconds. Fireline is strong enoguh to pull your rope up, it (fireline) often breaks at a MUCH higher load rating that is on the package. I have 80lb Fireline break at over 130lbs loads.

small, COMPACT, light, effective.

takes practice.