In my quest to try out exotic filaments, I was excited to discover that I could purchase PCL on a spool rather than the usual pre-cut lengths that 3d pens typically use. This low temp PCL filament produces prints with a satisfying feel like a hard plastic rubber. Sticks very well to a PEI print bed with heat turned off, even more so than PLA with heat on. Layers bond very strong and, unlike PLA, the prints stretch and contort under stress instead of cracking into brittle pieces. Another bonus is that you can submerge in hot water for a bit to soften and reshape if needed. I printed at the hotter end of the range at 110 C to reduce force needed to extrude quickly. Remember to prepend your gcode file with M302 P1 on Marlin based firmware to disable cold extrusion checking since this prints relatively cold. Obviously, don't want to use this for outdoor parts due to the low melting point but that is also true for PLA. Main disadvantage is that PCL filament is currently more expensive and less readily available than PLA or PETG for example.