Yeah, you get a length of chain and make it in stone weights (16 lbs). Thread an 1/8 inch cable through the chain to make it a small bundle and connect the weight with some cable clamps.

Now use a quick link (like a chain link with a threaded gate) to connect the cable to a handle (I use one from a cable weight machine). Try to make the whole bundle approximately the same length as the real implement (18 inches for the WOB). Add as many chain bundles as you need to get to the proper weight (28 or 56 lbs).

The chains dont tear up the grass and wont damage asphalt or concrete either, and they feel just like the actual implements.

You can even use one 16 lb chain on a PVC handle with a short metal pipe collar for the hammer.