Stretchable Floating Material?

Hi, I am new to the forum and the world of 3D printing.

I have a simple product that I want to create but it needs to have certain properties:
-I would like it to easily float in water, even carrying an additional objects weight. I also thought about printing a void so an air chamber would add the buoyancy. I will have to experiment with the objects weight and the buoyancy of the material
-It must be flexible with the ability to stretch similar to an o-ring. This item will be fit over different shaped "stems"
-It must be able to be shaped and stretched many times without damage and the ability to return to its original shape
-It must not be affected by UV and water

After doing some initial research, it appears TPU or TPE might be close to what I am looking for. I have no idea on the buoyancy however.

I am completely new to this and do not own any 3D printing products but am anxious to learn and experiment.

Thank you very much for the help!

you need to find out the density of the filaments you're looking at.
For starters on the tpu: ninjaflex and filaflex are the most common.

As long as a 3d printed object is watertight - it will almost always float.
By it's nature most 3d printed objects are a thin solid skin and a mesh or cell like interior which is mostly air anyway.
So forget the density bit. As long as you don't print it solid (which would be daft) floating shouldn't be an issue :-)

Thanks, is there is good easy to use printer for TPU that you can recommend for a starter just getting into this? I assume chosing to print with a cell like interior is an option in the software included with the machine? I have had TPU phone cases before and the material did not stretch that much, expanding 2-3x would be great if possible.

Yes, you can specify infill density and pattern with all quality slicers.

Filaflex is great for stretchability and unique in that niche.
You need a printer that can handle it well such as the Lewihe and Witbox machines.
These are used by SLEM, a footwear design school over here in the Netherlands.
Ultimaker does not handle them too well. I have yet to try it on the Wanhao 5S mini and expect good results!

filaflex and ninjaflex are both pretty much identical in every test I've tried.

How large an object are you planning on making ?
Can't recommend a printer without knowing how large it needs to be.Be aware that good flexible filaments are not cheap.

Hopefully it will be fairly small...about 1" long x 1/2" diameter or so.

I was reading a lot of reviews and came across the Monoprice Maker Select 3D V2. It seems the machine can be made really well with a few easy mods. Any thoughts on that one?

yep a basically a wanhao duplicater i3

also have a look at the monoprice mini. Smaller build volume, probably better for precision prints.