Simply, this is a filament sample spool for 1.75 filament. Is another one needed? Probably not. But I had a specific need that other spools did not have.

UPDATE: I was talking to someone that was having difficulties screwing the two halves together. They were using a printer that I never heard of before. So to help out, I created and uploaded two additional stl files. These two files are the base half for both the standard and thick spools. These files have the thread 1mm smaller, which worked for this individual. The top half of each spool does not need to be changed. So if you are having difficulties screwing the two halves together, download the stl file called "samplespoolbottomsmall.stl" for the standard spool, or "thicksamplespoolbottomsmall.stl" for the thick spool.

I get more than a dozen samples a month. While most people print their sample and are done, I leave the unused part on the spool. Many times I need a small amount of a specific filament. Well, therein lies the problem.

The other sample spools I had did not have a place for the end of the filament. I could usually find a place for the end, but the the spools would not stack correctly on my shelves because there was always the end of the filament sticking out. Furthermore, the end would sometimes fall out, leaving me with a tangled mess.

So I decided to design the super greatest ever spool for filament samples. (OK, maybe I overstated that a bit.) After all, it was just for me so I was not considering what other people may, or may not like. This thing is strong, yet has openings to easily see how much filament is remaining. Additionally, I have 12 places to put the end of the filament in, without the end of the filament getting in the way when I stack them up. Furthermore, this design keeps the spool securely wound because the end is held firmly in place.

The first picture is a render in Cinema4D, the second picture is an actual print, and the remaining pictures are renders of each part in Fusion 360 (including the thick version.)

Print instructions

This is to be printed in two parts, the top half, and the bottom half. I have printed many of these in PLA, PETG, and ABS. Leftover remnants of PLA is the main material I use for these. I print them in ABS for samples of TPU, polycarbonate or other hygroscopic materials that need to be dried prior to printing. PLA will not take the heat of dehydration.

The Included gCode Files
I have included two gCode files all set for PLA. One file is for the top half, and the other is for the bottom. The files are prepared for the MK3/s, but also work fine on my MK2.5s.

Printing the stl Files
There are two stl files, the "top" and the "bottom". I have also included two additional stl files for a thicker version for larger samples. Again, just print each one. Layer hight of 0.15 and 0.2 both work. Infill can be anything above 15%, but I see no reason to go above 20%. Supports are not needed. You can print both parts at the same time if you have a 300x300mm print surface as they will both fit (I usually print these together on my large printer.)

Using the Spool
The two halves screw together. There is a small hole in the center that you can place one end of the spool. Then on both the "top" and "bottom" halves of the spool, there are a total 12 holes that you can use to put the other end through. I made a lot of these holes so you will not waste much filament trying to reach a place to hold the end. It's a spool, not much more to it than that.

Final Comments
I know there are a lot of sample spools available, and here is another one. This fit my needs, maybe it will fit yours as well. I included the step files if you want to modify anything. And of course, just let me know if there is anything I can change to improve this for you.