Stratasys is claiming infringements on patents it owns (included ones acquired from Makerbot) on things like purge towers, heated beds, and force detection. Many of them things common to most FFF/FDM 3D printers.

Its an interesting coincidence that this lawsuit against one printer maker is happening on the same day as a new product announcement (the Prusa MK4s) from another major printer maker.

In two complaints, filed in the Eastern District of Texas, Marshall Division, against six entities related to Bambu Lab, Stratasys alleges that Bambu Lab infringed upon 10 patents that it owns, some through subsidiaries like Makerbot (acquired in 2013). Among the patents cited are US9421713B2, "Additive manufacturing method for printing three-dimensional parts with purge towers," and US9592660B2, "Heated build platform and system for three-dimensional printing methods."

There are not many, if any, 3D printers sold to consumers that do not have a heated bed, which prevents the first layers of a model from cooling during printing and potentially shrinking and warping the model. "Purge towers" (or "prime towers" in Bambu's parlance) allow for multicolor printing by providing a place for the filament remaining in a nozzle to be extracted and prevent bleed-over between colors.