The decathlon weight 500g pakets of sand)jacket is about €20.
How easy is it to make your jacket 10kg? Are the coins easily removable? Do you have straps to keep the weight 'tight'?
It's very easy. I'm using the cheapest weighted vest that I could find and it came with blue bags that I've just filled with coins. You don't really need straps to make the weights tight because the money just kind of spreads inside of the bag and doesn't move at all once it's there.
It's on my todo list to 3d print some containers to replace the bags with actual "money rolls" so that I can remove them more easily.
Maybe you've already considered and decided paper wouldn't work, or maybe you want the fun of working with a 3D printer, but my initial thought:
Would it not be simple to create rolls of coins by simply wrapping a sheet of paper round a stack of them, once or twice around, a little bit of sellotape to hold the paper in place, including folding it over at both ends and taping there too? I'd imagine an A4 sheet would be more than enough for each stack of coins, cutting off what isn't needed, and since you wouldn't care about them being beautiful you wouldn't even need fresh paper and could just use paper that would otherwise go into recycling/trash (letters received, junk mail, etc.)
edit: I did a quick search which both confirmed people have made coin rolls using simple paper, and also that it's highly likely banks will offer pre-made paper holders for the various coin sizes that you can just ask for and get for free (with the bank assuming you'll be bringing them back full of coins - you could either ask for as many as you need, or just one per size and use it as a template for making more from plain paper like this guy does: https://m.youtube.com/watch?v=AvsOkp_WPxY )
That's a very good point. I wonder about the durability of a paper based solution, but 3d printed rolls might also be suboptimal in that regard. This needs some experimentation.
I'd imagine that if paper alone wasn't strong enough for long term use, using sellotape to cover the entire roll such that the whole thing has a layer of tape on top of the layer of paper would make them pretty durable and add very little time and cost to it. (But I've not done anything like this, so my guessing could be bullshit - happy experimenting!)
