Yeah that would be the challenge. It’s probably easier to pickup decent priced glass ones. I am based in Germany, and I’ve managed to find a few options at the correct size. Just need to double check the cap fitting.It could work. I remembers seeing ones that did not have seams. The challenge would be finding baubles in 5cm with the iridescence and no seams. It took a fair amount of trial and error to find the correct ones in glass. My Christmas tree this year is covered in clear glass baubles .
For reference, these have no seam. https://www.amazon.com/dp/B076DLSSTS