I made a homemade adjustable kettlebell last night, like this:
It's all standard black iron pipe & fittings
The handle is 1"x6" nipple
That is threaded into 2 1" elbows
The nipples going down are 1"x5"
Then there are 2 1" Tees
The weights go on a 3/4"x12" nipple
That pipe has two 3/4" end caps
One of the caps is left loose enough to hand tighten.
I'm going to clean it up with degreaser and then paint it matte black. I found that the old pancake weights, like Cap still makes, fit fine, but the Weider weights wouldn't slip onto the 3/4" pipe. I'm going to fill in the exposed threads with Bondo and sand it all down before I paint it. I'll post pictures of the final product when I'm done.