Printing hollow things and then filling them with resin/concrete/etc...

Printing hollow things and then filling them with resin/concrete/etc… Is this a thing anyone’s tried? The concept here is to print heavy, sturdy things whether they are figures or, in my imagination, acoustically inert loudspeaker cabinets. I have a Prusa Mendel with PLA plastic.

Was just actually thinking about this today, printing something with a honeycomb infill, and then filling the inside with epoxy to make it ultra sturdy. If/when you do it, document it and do a writeup.

One problem with this is that anything you pour into a hollow object will shrink while cooling or curing. It might not be am issue for smaller figures, but i’d guess that with loudspeaker housings (that should take up most of your build volume to sound nice) it might become a problem.

That’s a great idea! To go a step further, you could even drop the filled piece into an acetone bath and remove the ABS/PLA form. Just a couple weeks ago I made some successful resin and silicone casts using 3D-printed molds, so I think your idea would definitely work!

Another thing to consider is that honeycomb infill produces sealed cells that would be difficult to get a resin into. You can’t just pour a fluid into a single hole in the top and expect it to fill all of the interior space. Other fill patterns will not (reliably) seal off separate cells, but none intentionally leave channels for such a fluid to permeate, and they may not reliably do so. Some shapes can be made entirely hollow, and some can’t. In any case, you can’t really rely on the internal geometry looking the way you expected beforehand when the slicer is done with it.

@Jason_Webb The admiral turned out really well. Very nice.

Nice blog, I’ll keep it in my rss-feed. As for the filling part I only have to ad this; Check out the curing/chemical process, as I’ve noticed that PLA can slightly reform when heated up to 70°C or above.

Unless you had a way to cool it and cure the concrete/resin in a larger mould so when it shrinks it will be a equal size and the cooling will let you slide it into the speaker … unless im barking up the wrong tree haha

That’s the way concrete printers work. They print a couple of thin skins of crappy quick-set concrete, and then flood-fill with Real Man’s Misogynistic Concrete™.

What if you used PVA and a dual extruder to make a water-soluble infill?

I’m not that taken with water-soluble support. Models take ages to drain out…

I’ve done this to an extent. What I did was make the inside completely hollow(the software I use has a hollow feature) and the filled the gap between the inner and outer wall. This allows you to do a multi-pour if you need to.