Possible idea for printer waste/poop use: molded solid infill for large prints?

So I was browsing silicone molds thinking about ways to reuse failed prints and waste/poops, as one does, while waiting for one of my biggest prints yet (over 500g) to finish, and something occurred to me. I did a quick search and scan and couldn't find anyone else talking about it, so decided to share my thoughts to get your feedback or inspire others.

If you're anything like me and trying, generally, to conserve filament, you probably don't print things with a substantial infill percentage, particularly when they're large. But, if you're like me again, you might also be disappointed when you go to pick up said large prints and find them feeling too light. There's something nice about certain objects having heft to them. Something like a bust, for example, would benefit from extra weight. I've heard of various ideas for filling with putty and the like, but haven't heard anyone suggest this:

Melted down waste filament using molds results in a pretty hefty end product, since it's basically like 100% infill.

What if, when printing a large object, you added a square void, the same size as, say, one of those ~2" whisky ice cubes that you can get a cheap silicone mold for. Add a pause in the print when the hole is complete, drop in a pre-molded plastic cube made from your waste, then resume the print? You could add multiple voids for larger items.

Not only are you not wasting usable filament with extra infill, you're saving useful filament from printing unnecessary infill, and recycling the wasted filament in a way that adds actual value (in this case, extra heft to large prints, which are presumably going to be long-lasting items, particularly if they're going to be sanded/puttied/primed/painted.)

Sure, if you're molding the waste anyway, you could make one of those cool skulls or something else that's "useful," but how many skulls or dragons or trays can you make (assuming you aren't selling them) before you've got too many? Making my meaningful prints more substantial in terms of weight and encasing the waste within seems like a better use for the waste. It's free infill! (Of course, one could have always done this for prints by adding voids and pauses and adding lead ballast or some other form of weight, but I haven't seen anyone using waste filament for this purpose.)

I'm thinking you'd want the void to be a tiny bit larger than the recycled cubes, since they may not be perfectly sized since the mold has some give (unless you cut/sanded the cubes to size after) and then you'd probably want to add something in first to make sure the weight doesn't shift/rattle. Molten plastic would be ideal, but since we're operating in the middle of a paused print, I wouldn't want to risk screwing something up. Epoxy would be fairly permanent, too, in case the remaining print fails and you need to re-mold, so I'm thinking something like white glue, which is easy to melt with hot water and remove if you need to scrap the print and start over.

(Likewise, you could just dump loose waste/poops into the void, then fill with glue so it doesn't rattle. That's less work melting molds, but it will add less weight, though it still saves you infill filament.)

I'm also thinking that just after the void, the next couple layers might be best suited to be a "lid" for the void which you would pre-print, just a few layers at 100% infill tile that will precisely match the lid of the void, so you can drop that in over top of the recycled filament weight (which might have an uneven surface otherwise, or if you're using loose scraps to fill; maybe add some more white glue before pressing the tile in to lock in the cap) as a platform to ensure the next layer prints nicely (though, if you're confident in your bridging, that's probably unnecessary.)

Anyway. Not sure if this is a good idea or a stupid one, but I figured I'd share in case it hadn't occurred to others and they'd like the idea as well!