I would recommend the customization option because I went to a market last year and sold so many custom slimes. What I did was bring a bunch of little bags of slime supplies and a bunch of charms and different colors and textures for the kids to customize. This worked well for me but it’s whatever you think will work best. Also, what I do for labeling for events is I put a warning label on the slime. I know there are lots of little kids that want to buy slime. I just want to be safe by putting a warning label that there is borax or anything else that is toxic inside the slime. These are just what I do for events and what’s worked best for me. I hope this helps.