1

Is ninjaflex waterproof? I would like to fill ninjaflex baloon with water…

I would like to bond 2 ninjaflex parts together without harming elasticity.

Is there a way to do it?

I would like to smooth the surface of the Ninjaflex. Is there a way like using acetone vapor for PLA?

2

I use NinjaFlex to make gaskets that work for sealing water fittings.
When placed under compression, the small gaps etc that cause leaks are
squashed and they hold without leaking.
…
I recently made a bulb duster that needed to be waterproof.
After printing, I tested for leaks and sure enough it was leaking.
I coated the inside of the bulb with Krylon Fusion paint and left it sit for a week to dry out.
After the Krylon dried, I had no leaks and the part was still flexable.
I hope this helps you in some manner.