This Makerworld upload is a collection of a variety of spool parts, primarily to be used with Bambu Lab printers, although as I have tried to make them as universal as possible, they should also work with most other printers if needed. I had the original design on Printables, but I have now taken that down, and updated it with this. Originally, the purpose of this was to design an empty spool system that can be filled with weights and/or desiccant beads to be used in the Bambu AMS. Now that the A1 Mini and the AMS Lite has been launched, the previous spool design does not fit on the AMS lite, so I've done a complete re-do, with many improvements over the prior design.

Like the rest of you, I do not want to be re-spooling filament, and in a perfect world, all spools from various manufacturers would work properly on both the AMS and the AMS Lite, but that is not the case. Anyone who has used the original AMS knows how picky it can be with spools. Some manufacturer's spools don't roll very well in the AMS with not having enough surface area on the roller spool lips for the AMS rollers to grip onto. Another common problem is when your filament is nearing the end, the weight of the spool is too low, causing the spool to hop around or not retract/feed inside of the AMS. Some spools are too wide, some are too short or too tall. There are multiple fixes available besides this to alleviate some of these problems such as spool ring adapters, using electrical tape on the spool lips, weighted inserts for the spools, the Hydra mod, but I wanted a more complete solution that lets me use any filament I want, re-spooling as minimally as possible, without voiding my AMS warranty. This is what I came up with to alleviate all of my issues to have piece of mind when printing out of the AMS.

The AMS Lite is a much better design in regards to spool compatibility, as it grips from the inside of the spool, instead of relying on rollers, but all spools still do not fit on it, and if you have both an AMS and AMS Lite, and are swapping spools between them, it's preferable to have something that "just works". What I have been doing is whenever I buy a new roll of filament, if it fits on the AMS Lite without issue, and if it rolls in the AMS, and I can get an inner spool weight inserted into it, I leave it as-is. If it's a cardboard spool, the plastic spool lips are rounded, or the spool's inner hole, or outer diameter will cause a problem with either the AMS or AMS Lite, then I re-spool onto an empty Bambu spool, if I have any lying around, or I print one of these to use. When using my spool weight with a Bambu spool, it fits in the AMS nicely and spins freely. There is an inner wall between AMS slots that keeps the spool weight from falling out, check my uploaded pictures, I've included some showing that.

There is nothing wrong with Bambu's spools, other than I don't have dozens of them on-hand whenever I need one, and as they are $11.99 with a lead time to get them to me, printable spools come in handy in a pinch. One advantage my printable spools have over Bambu's is the empty space between the inner ring and where the filament winds onto can be utilized with either desiccant beads and/or weights. Everyone has their own system for keeping filament stored and dry, such as custom humidity controlled cabinets, airtight plastic containers, vacuum sealed bags, etc. I keep all of my spools on filament racks that run around all four walls of my printer room, above all my equipment, which lets me store roughly 200 rolls. I use large ziplock bags when storing spools, and if it's a Bambu or other AMS/Lite compatible spool I'll throw in a container with some desiccant in the bag before sealing. If it's one of my spools, I use the vented design, which has space within it for desiccant beads.

I've made a lot of options to try and meet a variety of people's wants/needs in regards to weights and/or desiccant. The solid, non-vented spool can be used empty, just like an empty Bambu spool if desired, or it can be filled with weights to help in the AMS. There is also a vented version with slits on either end to allow airflow to desiccant beads. For inner spools, there are even more options, such as completely solid or vented designs, and some that have chambers, where you can use weights in two chambers and desiccant in two others. This is my preferred design myself. Two chambers filled with weights is plenty of weight even when a spool in the AMS gets very low to keep it from jumping around or giving you the failed to retract error message. The two other chambers filled with desiccant also helps to keep the humidity down in the AMS. I keep these AMS inner spools in the AMS at all times, and then insert them into a roll when needed. This keeps the beads from having to be recharged very often. When they do need to be recharged, I put the entire inner spool in a filament dryer, and when they look good again, put it back in the AMS.

To assemble the various parts, heat-set inserts and M3 screws are required. This design uses less of them than my prior design, which helps costs. If you have a single AMS, you only need to print out four inner spools and four inner spool caps, in the design of your choice (solid, vented, split, etc.). Each inner spool uses needs four heat-set inserts and four M3 screws. For the main spool halves, Spool Half B is a common design, and is used for both the solid and vented Spool Half A versions. None of the Spool Half A designs need any inserts, but each Spool Half B requires eight of them, four on each side. Four of them are used with M3 screws to hold the two spool halves together (A+B), and four of them are used to hold on either a spool cap or an inner spool. Use whatever desiccant beads and/or weights you see fit. I like the color changing beads for visual indication of their humidity level, and with my previous design, people were using everything from small rocks to nuts & bolts. With my new design, I've been using small lead balls in my eight AMS inner spools, which are very heavy for their size.

You can source your parts from a variety of places, but I'll include the links of the parts I'm using for reference.

M3 x 3mm brass inserts
https://www.aliexpress.us/item/3256804661875731.html
With brass inserts, there are a ton of different designs, with some that hold better than others. I've had good luck with these.

M3 x 6mm socket head screws
https://www.amazon.com/dp/B089KR3XHR
These are used to hold the different caps/inner spools on.

M3 x 14mm socket head screws
https://www.amazon.com/dp/B089KQV2WV
These are used to hold the two spool halves together.

You will also need a soldering iron to press the inserts in, and a dedicated insert soldering iron adapter like this helps:
https://www.amazon.com/dp/B09ZNSMVZG/

If you've never heat-set inserts before it is extremely easy. You can watch some YouTube videos if you like, but basically, you put on the adapter tip, allow your soldering iron to get up to temp, then place the insert (the right side up, it matters with some designs) over the hold. Then use the soldering iron to press it straight into the hole about 90% of the way. Then remove the iron, and use something flat and heat resistant, like a piece of metal (I generally use a metal scraper blade) to press it in the rest of the way. For the four inserts that need to be put recessed down in Spool Half B, I use a spark plug gapper, but if you have anything on-hand that is flat on one side and heat resistant, that would work also.

https://www.amazon.com/GearWrench-3293D-Metric-Spark-Gauge/dp/B000CODE9S/

The lead weights I'm using for my inner spools are from here:

https://www.amazon.com/gp/product/B0034ZG9US/?th=1&psc=1

Like I said before, you can use whatever you want, and if you have a local gun shop or diving shop around with re-loading supplies, you might be able to get some lead shot from them cheaper.

When deciding what you want to print, start with the inner spools. Decide if you want the solid ones with just weight in the middle, or the completed vented design or the split. I have "Inner Spool AMS Packs" in 3MF format uploaded that have a set of four inner spools and caps in a variety of choices. You can adjust the printing parameters to what you like, but I'd recommend arachne walls over classic as printing the vented designs with classic is a little screwy with the vent fins. You only need to print four inner spools total for each AMS unit you have.

If you are using spool refills, Bambu's snap-together spools are going to be your easiest choice, as disassembling/re-assembling mine requires an allen wrench. If you are re-spooling from another roll, decide if you want the solid or vented design, then print the relevant halves and then assemble.

I weighed up some of the assembled parts for comparison:

Vented Inner Spool, filled with desiccant = 156g (0.34 lbs)
Split Inner Spool, filled with desiccant in two chambers, lead shot in the other two chambers = 428g (0.94 lbs)
Solid Inner Spool, filled with lead shot = 796g (1.75 lbs)

Vented Spool, filled with desiccant (with no inner spool inserted yet) = 250g (0.55 lbs)
Solid Spool, filled with lead shot (with no inner spool inserted yet) = 712g (1.56 lbs)

So you can see, using both a solid spool and solid inner spool, both filled with lead shot is a total weight of 1508g (3.32 lbs), and that's with no filament on it yet. I personally feel that is total overkill and that much weight is certainly not needed to hold down a spool in an AMS. That's why I'm using vented main spools with split inner spools, which have a combined weight of 678g (1.49 lbs). But you do you, I've uploaded a lot of options so you can pick and choose what you want.

You can print these in PLA as long as you aren't going to submit them to high temperatures. If you plan on putting the spools or empty spools in some sort of oven or filament dryer that hits high temps, you might want to print the relevant parts in something with a higher glass transition temp, like PETG. I've printed all of my inner spools in PETG, and most of my outer spools in PLA, but some in higher temp material, depending on what is spooled onto them.