How to add items to Guncadindex?

I was looking for cool accessories for the Kel tec sub 2K. I found these two items (a stock and charging handle) on printables, but noticed they were not showing up when I searched them on the index. How can one get these added to the index so others may find these more easily if they are fellow sub2K lovers?

Charging handle: https://www.printables.com/model/981151-kel-tec-sub2k-dual-finger-charging-handle-remix

Stock: https://www.printables.com/model/980855-sub2000-dual-mag-stock