It was a hassle needing to disassemble the filastruder if I wanted to take the hopper off, or change it to horizontal, and I like the two piece removable hoppers. However I couldn't get an adequate pellet feed from them. The 2 liter bottle hopper covered around 13mm of the opening with pellets and gave me a really slow feed rate. This one covers about 22-26mm of the opening. It holds together with M4x12 screws, and features a sliding door for dumping the pellets. I made an opening in the top of the chute to make it easier to see what is going on, then found that you can't see it due to the case or wooden support. It doesn't affect the functionality and at least saves a little plastic.
The hopper has a slot in the front for keeping track of the level of pellets. I cut a piece from a clear plastic report cover to make the window. A cap helps keep moisture out, and the underside would be a good place to stick a desiccant cartridge with some double sided tape.
Print the funnel with low infill, like 10% to keep it from becoming massive. It is a tight fit with the hopper, so any bulging at the corners of the hopper will need to be trimmed. Put them together before attaching it to the barrel.