So you are watching the Anycubic you tube video below on how to replace the FEP. When it comes to adding the slack so that its tight when the frame is screwed in, they tell you to use a Bottle cap as that's about right, 13mm tall and about the right width ..
After going through all the coke bottle caps etc in the house and finding them the wrong size, I ended up making this quickly. Creates a perfect tightness to the FEP when used.
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