Decorating soft plastic

[nottoocreative]

This is kind of a follow up and a request for any ideas you may have...I posted a question a few weeks ago under Techniques about how to decorate a plastic beach bucket so that it wouldn't rub off too easily in the sand and water. The idea is at my dd's 6th bday party the kids will each decorate their own bucket. I do have foam stickers if they don't care about them getting ruined when used, but I wanted an option for something that would last for at least a few trips to the beach. I bought cute foam beach theme stamps and stencils.
I tried EVERYTHING, I think, and here is the results of my limited experiment (I sacrificed one of the buckets):
StaZon only kind of works if you prep the surface first with rubbing alcohol and let it dry for over a week. I used Opaque Cotton White. It can still be scratched off but not too easily; it will do for the stamps. I actually contacted Tsukineko and they said it wasn't meant to be scratch proof, just "decorative."
Sharpies work (but they're all dark unless you have white plastic) but they can actually be mostly rubbed off with the alcohol (d'oh found that out while prepping for the Stazon) (leaves SOME faint lines)
I JUST got a Sharpie Paint Pen but want to let it "cure" a week or so before testing; my guess is it will scrape off like the Painters pen but who knows.
Slick markers work also, but again the colors all look dark. The alcohol didn't rub them off.
Zig Painty was a little less durable but not too bad, after prepping with alcohol and drying a week, I could hardly scrape any off with my fingernail and the alcohol didn't take it off. Nice because they are opaque (mine was light blue on an orange bucket).
Pilot metallic marker Works the best! Opaque (mine was silver) and couldn't scrape it off easily (again after alcohol prep and a week of drying), nor did the alcohol take it off.
Elmer's Painters Pen looks great (I used white) but scratches off easily with a fingernail, so probably won't hold up in sand

So the winner is the Pilot metallic marker! I was shocked, I just tried it because I happened to have it from my wedding (used to sign the guest book). I'd say the Zig Painty is a close second and the Sharpies will work, too (just mostly dark looking).

Thought I'd just pass along my results and see if anyone has had success with anything else. BTW, this is SOFT plastic (beach bucket) so it does not act the same as hard plastic (like a clear acrylic box or something) or glass.
Have a great night!

[nottoocreative]

No other experiences or suggestions?:(

[Lauz]

I really don't know, but what about lumiere paint or something similar?? would that scratch off?

[nottoocreative]

Just an update for those interested:
I found some Plaid Paint for Plastic on clearance at Michael's, which requires a primer on soft plastic...so I wanted to avoid that. However, the primer was on clearance also, and I found that it was really thin so it only took a little to prime the whole thing. I primed all of the buckets already, so they are ready to decorate at the party (had to do it outside, the vapors were overwhelming). On my "test" bucket, the primer made a HUGE difference with even the Painter's pens, Stazon, Sharpie paint pens, and metallic markers so now they can be decorated even without using the "Plastic" paint, and they do NOT scratch off!!!!!! I'm so excited...and if anyone ever wants to decorate a soft plastic, I recommend grabbing up some Plaid primer--one bottle goes a long way (I did 24 big sand pails twice and still have some left).