Still working on my costume

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I would like to know a method for crafting fake potion bottles for shows, i want the bottles to be:

• Approximately the size of an apple
• Resist the pressure of being transported in bags
• Resist weaker impacts
• Don't leak any liquid
• Not considerably heavy

Aditional info:

• It doesn't need to be made of real glass
• It doesn't need to contain real liquid
• I don't pretend to craft the "bottle" itself, but I want to know what may be used to represent it (A light bulb, a medicine bottle, etc...)

Visual representation:

PS.: I'm not sure how to tag it so feel free to edit it