I haven’t actually tried this for anything real yet and not actually with TPU - but I think it is possible to do a multi material print that doesn’t have too many filament changes by having the TPU on the external spool and the PLA in the AMS - but tricking the AMS into thinking it is feeding both lots of filament.
It does involve manual intervention for every filament change.
It was a little bit fiddly - but this thread explains how I managed to do it. External spool + AMS
Other alternatives that I have considered for TPU support are:
- Create the support interface externally. i.e. Design the model with a tiny gap between the supporting TPU and the actual model. Insert a pause in the print at the point when the support has been printed. Apply something on top of the support like glue or blue tape. Then continue the print.
- If you have access to a Palette2 or 3 use that to create some spliced PLA/TPU filament and feed that in through the external spool.