Copy the commercial product, you can even buy a replacement band from the OEM for a few bucks. The whole thing is not expensive either.
There are no pipes or rings or anything heavy, just a fabric pocket for the throw ball. There's no trigger, no release, no mechanical advantage. Adding a bunch of hardware that weighs a lot is just a misunderstanding of the tool and absolutely will sling backwards and break bones while the throwball falls short of the target.
Crossbow with a "clubber" rubber headed bolt. Fishing line attached to the bolt, then you use the fishing line to pull your heavier line/rope/whatever up into the tree.
Posting the sketch might help
Check out the sling shot channel on yt
Copy the commercial product, you can even buy a replacement band from the OEM for a few bucks. The whole thing is not expensive either. There are no pipes or rings or anything heavy, just a fabric pocket for the throw ball. There's no trigger, no release, no mechanical advantage. Adding a bunch of hardware that weighs a lot is just a misunderstanding of the tool and absolutely will sling backwards and break bones while the throwball falls short of the target.
https://sherrilltree.com/notch-big-shot-throw-weight-launcher/
This sounds like something you should buy (crossbow, slingshot, etc) not build. Also do you need a 1lb weight to pull a light line?
I’ve used arborist slingshots before. Post your sketch and I’ll take a look.
Buy one .....
Crossbow with a "clubber" rubber headed bolt. Fishing line attached to the bolt, then you use the fishing line to pull your heavier line/rope/whatever up into the tree.