Bottle bottom lid

I cut the bottoms off of pop bottles to make my rPET filament and wanted to use the bottoms to store little items.  So i made this ring and lid that fits onto the bottom of the bottles. 

Designed for 16.9oz Mtn Dew bottles but im sure it would fit other 16.9oz bottles.

I cut the bottles on a line thats about 1 1/4" from the bottom which leaves just enough room to push the ring on the bottle bottom.

Theres a recess on the top of the lid so that bottle bottoms can be stacked!