Add Weight to Hollow Models

I am printing a 25cm tall character and to save on material costs, I hollowed out the model and left holes for excess resin to drain out. After I clean up the print I want to fill the hollow sections with some kind of material to add weight the the print. Can anyone recommend a material to do that?

Is injecting melted monster clay into the gaps a good idea? I am concerned about a melted material expanding and contracting inside the print and damaging it.

Any thoughts would be great! Thanks

Could fill it with playdoh for a fairly low cost or molding/sculpting clay. That’s nice and dense. I’d be concerned about hot materials unless you’re using well cured high-temp resin (which i can’t imagine you are)

Plaster could be a good, cheap option. It’s not super dense (~20% more than resin), but cheap, hard, easy to work with.

I’d recommend a two part urethane resin… Smooth-on does a number of different types. Depending on how big the holes are, you’ll probably need to mix and inject with a disposable monoject type syringe. I typically mold the 3D printer figures and reproduce them in this type of resin, but you could certainly use it to fill a hollow printed part to give it the heft of a solid printed part… and the resin is cheaper than FormLabs UV resin!

So many different ways.

You could fill it with sand, then seal the hole, that’s just about the cheapest most efficient way.

Or if you need it to be even heavier, you could fill it with lead shot (for shotgun shells). If the drain hole in your model are the typical ones (2-3mm), you can buy #9 or #10 lead-shot really cheap. If you stuff it really well, it won’t rattle around inside the model.

Just don’t use PVA glue to ‘fix’ the lead shot in place. There is a reaction between the lead and the PVA and the products expand and con split the model.

1 Like

Very interesting. Didn’t know about this, so I read up on it. Thanks for the heads up. :slight_smile:

You can use polyurethane resin, I think is the cheaper and easy way to do. I use it in my molds. I think is better is you use a slow cure polyurethane resin to give you more time to fill the model.