There are a few different types of filament that are flexible. The three that come to the top of my mind are NinjaFlex, FlexPLA, and TPE. You can search for the 3D printers that use that material by using our advanced search feature.
I have tried flexible filament from NinjaFlex and they’re pretty good but I noticed that you’ll have to clean some tiny threads that appear in the printing process. Also, I had to raise up the temp just a bit and lower extrusion speed, too.
Flexible materials does not need to be very difficult but some things needs to be kept in mind. Like for instance:
-a good feeding of material - low friction all the way to the melt-zone (or else the print will be uneven)
-a good extruder feeding mechanism that keeps the pressure on the softer filament (spring loaded is good)
-a good support directly under the feeder wheel so that the filament cannot escape
-start slow and ramp up the speed to check the limits
-nozzle diameter matters: small gives more counter pressure -thus slower speeds
-nozzle diameter matters: bigger gives a better bond between the layers and makes for higher speeds (I use 0.7mm)
-different soft material filaments will behave differently (for instance my ETPU will not give much problem with “spider web”)
-Be careful with what print table surface you use, if unlucky the material can bond so hard that it is impossible to separate (I personally use blue tape, glass or PVA-glue right now)
This is my logo printed in my own electrically conductive TPU (its available also in a sample-bags)
I have just started testing PP filament. Didn’t make it yet… the material that I am using takes tooo much time to lose heat. This way the nozzle creates that mess. Like making a cake … a cake batter.