Hi Vincent,
Here are a few of my thoughts on how I would go about it.
1. To make the glow in the dark words, you can cast them yourself or maybe you will be lucky enough to find some. If you are going to cast them yourself, you are likely to have to make a mold for them as well. We don’t carry a letter mold that makes letter small enough to go in a wedding band. You are also going to need a ring mold as well.
2. If you want the ring completely clear, then I would cast the ring using the technique in this bracelet: https://www.resinobsession.com/resin-tutorials/button-bangle-resin-bracelet-tutorial Depending on what color your letters are though, you may not be able to see them very well if it is clear behind them.
3. If you want a colored background behind the letters, you are going to have to come up with something. It could be metal, plastic, another resin casting, etc. The nice thing about this is you could adhere the letters to this background, then cast them together as one piece in the ring mold.
Does that make sense?