Originally Posted by Michael A. Jones
The first one I made weighed over 40# but was too heavy for my amateur self
I got the tube from a roadside tire repair shop; it was off a rig. It was big enough to fill with 40# of strictly sand. The large tubes can probably be bought from places like Tractor Supply or Gempler's. They run about $35 or more....My recent construction is 70/30 sand and some filler from my heavy bag for bulk.
I was specifically referring to a DIY slam ball. I've not seen a writeup yet where someone achieved more than 25lbs with sand on anything less or equal to a full size basketball. Anything bigger would be too cumbersome in my opinion. Steel shot would work but it's too expensive.
I actually did try my first sandbag yesterday though. It's a 50lb play sand bag double coated in heavy duty duct tape. Seems like it'll hold up but we'll see. For the grand total of about $12 I have in it, it's worth a shot.