I just played my first glow round this weekend with 3 Eclipse 2.0 discs. A cheap UV light worked fine. I bought one for like $8 at Harbor Freight. It worked great if I just used it while we walked between holes or waited to tee off. It glowed really bright for the duration of the hole but probably would have been plenty bright enough for 6-9 holes if needed.
I'll probably upgrade to a larger UV light like this one from Amazon next time, as a couple of guys had these and they seemed to work better.
https://amzn.to/3FaIwMs
I also had one of these laying around that I left inside my small Innova Standard bag, which seemed to help a little.
https://amzn.to/3VR1Q7H
I also had some leaded UV LEDs laying around, so I used a watch battery to power them and taped them to the underside of the discs. I don't think those really did all that much compared to the flashlight. If I could find some that project the light in the proper direction, I'm sure they would work better, but pretty much all of these 5mm leaded LEDs project away from the leads.
https://amzn.to/3TxNRC2
If you'd rather just use LEDs on your normal discs, you can use an actual leaded LED with a CR2032 or CR2025 3V coin cell battery. Just use tape to affix the leads on the LEDs to opposite sides of the battery, then use clear tape to connect the LEDs to the disc. I would stick with blue or white LEDs and use 2 per disc. Trust me, 2 LEDs on opposite sides of the battery looks way cooler in flight. Bonus tip, tape some of them off-center. It looks super cool. The batteries should last a couple of rounds. This is cheaper and more durable per setup than the ready-made sticky LEDs you can get from MVP or the like, and basically the same amount of work, because you'll need to tape those down too.
LEDs -
https://amzn.to/3TyKHhd
Batteries -
https://amzn.to/3gFlenJ
As someone already mentioned, packing tape can work, but it's not very durable. There's a flexible form of packing tape that works much better. Normal packing tape will also peel the stamps off the top of your discs. I've heard of people using Gorilla Crystal Clear Tape, Clear Duct Tape, or even Hockey Sock tape.