I don’t know of a good test. You should be able to use any printer’s heat bed for my method. You could put a bowl of rice or silica packets in the enclosure with the filament when it is drying on the heat bed. That should suck up all the extra moisture. My filament is not spitting like it was before which is good sign it worked. I will probably get a food dehydrator similar to the one in this video at some point, but the model he is using is currently $200. I like this style as it could also be easily used for filament or dehydrating fruits & stuff. I just don’t want to spend $200 on one, maybe near Christmas they will be less expensive. Since my wife is interested in dehydrating fruit, it will be easier for me to buy one of these. Some of the other DIY dehydrator ideas of the round version show having to cut away part of the enclosure making it unusable for its original purpose.
https://www.youtube.com/watch?v=1ZRAVdqy990