A dryer should solve a recurring problem in your printing routine. If you use one spool at a time, capacity you never fill adds bulk. If you run several materials, a single shared temperature can become the real limitation.
One spool is often enough
The SUNLU S2 is the compact option in this shortlist. Its declared 70°C ceiling covers materials whose own drying instructions fit inside that range. Choose on that requirement, not on a generic preset called “nylon.” Check the spool’s outside diameter and width against the current model before ordering.
Two spools without four-spool bulk
The Space Pi Plus fits a primary spool and a second color or support material. Both share the same drying environment. If one material needs a higher temperature than the other can tolerate, two spaces inside one box do not solve the mismatch.
Compare the exact Plus package on Amazon: a listing can offer several Space Pi variants under the same family name.
Four spools: capacity or independent heat?
The SUNLU S4 is worth considering when several standard spools need the same general temperature range. Its advantage here is throughput, not a higher heat ceiling.
The SpacePi X4 adds two independent chambers and a declared ceiling of 85°C. That is useful when pairs of spools need different settings. It is not a promise that every PA, PC or fiber-filled formulation can be dried in it.
Before you choose
Write down three things: your filament maker’s drying requirement, the largest spool you actually use, and how many spools must be ready together. The model that satisfies those constraints is a more useful shortlist than the one with the most presets.
Our single versus multi-spool guide helps size the box. For engineering materials, check the nylon guide before choosing a temperature class. The Amazon options below let you check the selected variant, current seller and package without copying a stale price into this guide.