A while back, someone sent me a product called the Ink Miser. Thanks whoever you are.
Ink Miser is designed to extract that last bit of ink from your Noodler's ink bottle. It comes in two version, one's called Intra-bottle inkwell and is meant to be put inside the bottle. The other meant to used outside the bottle is called Ink-shot Inkwell and comes with a dropper.
The intra-bottle inkwell is probably supposed to work only with the 90ml Noodlers ink bottles. If you use other brands of ink bottles, the ink-shot inkwell is the one to get.
To use the intra-bottle inkwell, you just place it in the ink bottle, cap the bottle, turn it upside down and back up, and the ink should fill that little cup. The inkwell basically brings the ink higher and allows you to reach it with the fountain pen. It works quite well.
As for the ink-shot inkwell, it's straightforward. Just use the dropper to fill up the cup and refill the fountain pen with it.
Each inkwell, at the time of this review, is less than US $10 on Amazon. It's worth the money. Don't pay more than US $10.
This product allows you to use up the last bit of ink from your ink bottle. It makes it more convenient to do so.