Armored Titan Serum Flask From Attack On Titan

You can print this and use twine and a whine bottle cork to make it look realistic.

I would suggest printing this out on tattered yellowed paper
"サイキョウ" "Strongest"
OR
"コウカノキョジン" “Hardening Titan”
and then gluing it on or you could just paint it on.

https://snkception.tumblr.com/post/118542535796/update-on-levis-serum

When used it would give you the power of the armored titan.