Printing the non-planar PLA part on top of the non-planar side of the PETG part. (Credit: Michael Wüthrich)
Most of the time FDM 3D printing involves laying down layers of thermoplastics, but the layer lines also form the biggest weakness with parts produced this way. Being able to lay out the lines to follow the part’s contours can theoretically strengthen the part and save material in the process. Recently, [Michael Wüthrich] demonstrated an approach that uses a modified Prusa Mini FDM printer to first lay out a part in PETG using non-planar printing, after which this PETG part was used to print on top of in PLA, effectively using the PETG as an easily removable support and leaving the PLA part as fully non-planar on both sides.

The modification to the Prusa Mini printer is covered on Printables along with the required parts. The main change is to give the nozzle as much clearance as possible, for which [Michael] uses the E3D Revo belt nozzle. This nozzle requires a custom holder for the Prusa Mini. After this the printer is ready for non-planar printing, but as [Michael] notes in the Twitter thread, he did not use a slicer for this, as none exists. Instead he used Matlab, a custom script and a lot of manual labor.

Non-planar FDM printing has been covered by us before, along with the need for slicers which can handle such more ‘exotic’ tasks. Hopefully with efforts like this by [Michael] such a future may be a bit closer now. If the waiting for this takes too long, or 3 axis printers seem a bit old-school, we were reminded via a tip by [Keith Olson] that it’s always possible to double the number of axes for more freedom, as in this video demonstration by [Fergal Coulter] (also embedded below), of a 6-axis 3D printer which also prints on top of an existing substrate.

https://www.youtube.com/embed/MrBOTG9cAJ8?feature=oembed