I have been using cheap wood mallets to do the final straightening of hot blades when forging. The main problem is they are to light.
Been brain storming for a few months and here's what I come up with.
The materials I used were:
2"x2"x3/16" square tube 2" long
3/4"x9" sch 40 black pipe
3/4"x3/16"x2" flat stock
1/4"x1-1/2" lag bolt
1-5/8"sq oak leg (Lowes) 16" long (makes 4 heads)
Note, this hammer is not used to remove the banana curve on forged blade. I still use a big oak stick for that.
Thanks for looking.

That's pretty slick, cooter. Kinda like a replaceable head mallet, without the big name ticket price. Very inventive!

nice idea, consider it copied! thanks for posting.

For some ornamental work I use a lead hammer, which is soft and heavy. To cast it I took toilet paper tube, stuck my handle in the side of the tube. I then put sand around the outside of the paper tube and poured my lead into the tube. Put a weight on top of the tube before pouring or it will float up. Melt and pour the lead outside because of the toxicity of the lead.

Nice utilitarian tool Mike. What's it weigh?

I keep my eyes open at yard, garage, etc. sales for wooden baseball bats, cut to size they make dandy mallets or sheet forming hammers and I usually give a buck or less per bat.

Frosty

Thanks for the comments.
Frosty, it weighs 2#. I also have used ball bats and also large wood table legs(seconds from a local shop) to correct the banana bends. I wanted something with more of a forging hammer cross section. The 16" legs at Lowes cost less than $5 and it's a repeatable source.

The NC version of the sledge o matic. Looks good Mike.
Ken

Very neat idea, I really like it and probably will end up copying it.

May I make a suggestion?

Make the tube a little longer and fill it half way with lead shotgun shot, then cap it. By doing this you will have a dead blow that shouldn't bounce when striking something, and it will transfer all of the energy into the part.

I use a Thor hammer with a wooden face. The hammers have a wooden handle and cast iron head that accepts rawhide/nylon/copper faces, I just replace the worn faces with a shaved down bit of oak they come in various weights upto 5KG