I bought the Cosori on Amazon and haven't had any issues and run it for 24 hours or longer sometimes. Later I was able to find a nice working four tray Nesco dehydrator at a thrift store for $10.
I’ve been using this one for a month or so and i like it a lot so far: COSORI Food Dehydrator (50 Recipes) for Jerky, Meat, Herbs, Fruit, Dryer Machine with digital temperature,5 Trays, Overheat Protection, ETL Listed https://www.amazon.com/dp/B07MPC7C8G/ref=cm_sw_r_cp_api_glt_fabc_Z23X1KGBTXQ7W759PCXF?_encoding=UTF8&psc=1
Found it: COSORI CO165-FD Food Dehydrator (50 Recipes) for Jerky, Meat, Herbs, Fruit, Dryer Machine with digital temperature,5 Trays, Overheat Protection, ETL Listed https://www.amazon.com/dp/B07MPC7C8G/ref=cm_sw_r_cp_api_glt_fabc_AX8FX3F8V6XMTEP2309V
Yeah you have to be careful with an oven as they tend to not be accurate and that can lead to a big mess if the temp spikes too high on you.
You can pick up a food dehydrator cheap though and it will do a great job. The keys are being able to adjust the temps and the trays can be moved/modified for space for the spools.
Here is the one I got (though I caught it for $40) and I just used flush cutters to clip the trays out: https://www.amazon.com/dp/B07MPC7C8G
There are cheaper models that will do just as good though.
Honestly this has been one of the better MMU "mods" I've done as filament that is giving me grief becomes perfect again after a trip through the dehydrator.
I went for the first 1.5 years without a dehydrator and was "fine". I am happier now that I have my dehydrator though.
Desiccant and dry storage will only do so much and will not actually remove water from the filament (at least not in any significant amount). All it's good for is maintaining things.
Another issue is that as filament ages it will become brittle in a manner that has nothing to do with water. The heating process of a dehydrator will help return it to a more flexible state.
Some people will put their spools in a food oven to perform dehydrating duties. This can work, but it is easy to ruin your spool as most ovens are not very accurate and tend to over shoot the mark when they need to warm back up. Depending on the oven, this spike can be high enough to fuse lower temp (e.g. PLA) filament.
Don't waste money on a filament specific dehydrator. Find a nice cheap food dehydrator that is big enough to hold a spool or two. Many of the cheaper ones are expandable where you just stack more trays on and then cover it. You simply cut the centers out of the trays. All you need is one that allows you to set the temps somewhat accurately and will stay on for your desired time frame.
I got a refurbed Cosori, cut out the centers, and have been happy with it. I can fit 2 1kg spools in it, or I can squeeze about 8kg in when I've respooled my filament to 500g bundles (stores easier without the bulky spools and means less is exposed at any time). I just set it to 120f for 24 hours for both PLA and PETG and then grab the filament sometime before the cycle finishes. I've had it run non-stop (well... stop and then an immediate restart) for 3 weeks at a time with no issues.
COSORI Food Dehydrator Machine... https://www.amazon.com/dp/B07MPC7C8G
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https://www.thingiverse.com/thing:4037764
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Dry filament and jerky
It's a gravity fit. I actually found out about it in some thingiverse comments, so I'll put details here for anyone else who wants to buy. My dehydrator is a mid-range one though because I wanted something good to last.
This dehydrator https://smile.amazon.com/dp/B07MPC7C8G/ref=cm_sw_r_cp_apa_i_Ls3AFb9FEWSPP
This cake carrier https://www.ikea.com/us/en/p/krispig-cake-carrier-20336407/
I threw out the bottom and drilled like 6 holes in the top/center to emulate the normal dehydrator lid.
I have one of these, COSORI CO165-FD Food Dehydrator... https://www.amazon.com/dp/B07MPC7C8G?ref=ppx_pop_mob_ap_share, it’s a beast.
I can easily fit 2 in it. I’ve checked the temp with a nice IR gun too and it is accurate.
I’ve been having great luck with this one. Printed some extensions to fit more rolls in it.
Been happy with this one: https://www.amazon.com/COSORI-Food-Dehydrator-Machine-Recipes/dp/B07MPC7C8G
Just used flush cutters to cut the centers out of the trays.
I think I can only get 2 spools in there at a time with the filament on the spool, but I respool my filament to smaller bundles for more compact storage which allows me to actually cram as much as 7-8kg in at once. There are also some extensions available on TV so you can further expand the capacity, but I haven't gotten around to trying any yet: https://www.thingiverse.com/search?q=cosori&type=things&sort=relevant
Just measured it and a 5 gallon bucket is about 20mm smaller than the trays. So I think you could simply cut the bottom off one and use it would work as an extension. Gonna have to give that a try...
https://smile.amazon.com/dp/B07MPC7C8G/ref=cm_sw_r_cp_apa_i_Ls3AFb9FEWSPP
Plus
https://www.ikea.com/us/en/p/krispig-cake-carrier-20336407/
gravity fit, just pop the rest of the dehydrator besides the bottom tray off, add the cake topper, put two filaments in, set to desired temp/time, done. Well worth it, better than the print dry boxes from esun and sunlu I've tried.