IMHO this dappen dish is way too big.
So big in fact that you can't actually put a small enough amount in sufficent for 1 set of nails or for a play on your nail trainer. You can't help but put too much in then have to use it over a period of time, which is not really recommended, even working on yourself or the nail trainer.
Why? Well, not only because it gets you into a bad habit that you may carry on when working on clients, but the monomer doesn't actually all of a sudden go 'gloopy' when it gets contaminated it is a gradual process. Therefore you will have done a few nails with it before you notice, which may lead to lifting or discolouration, and it also affects how you can pick up a bead in the first place, throwing off your mix ratio.
I also wouldn't recommend the storage in another jar for these self same reasons.
If I were you I would bin this one, and get another dappen dish more suitable. A nice small one that you can only use a small amount of monomer or still smaller than you have with a lid or cork.
The small glass ones from any Beauty wholesalers are cheap and way better than this. Or of course look into some of the other dappen dishes recommended here.
HTH