Piper2 is a coreXY 3d printer.

Piper 2 features:

• Use of cheap EMT conduit pipes for the frame.
• Self-replication – majority of parts are 3D printed.
• CoreXY.
• Stationary bed what allows to use 120-220V heating beds.
• Use of hybrid linear motion system 8mm linear rods are combined with 1/2 inch EMT Conduit.
• Variable bed size (defined by the length of 8mm guiding rods).
• Fixed 300mm print height (defined by electronics enclosure design)
• Single or Dual extruder support.
• Bowden extruder/s.

Piper 2 was presented at ERRF 2018.

Also, check my interview to Matt Snow:

All printable parts are posted at https://www.thingiverse.com/thing:3022836

By default Piper 2 features 300mm printing volume height (limited by design of electronics enclosure). Bed size is defined by the 8mm guiding steel rods to be used for example 4 steel rods 350mm in length will give you 250x250mm print bed. 380mm steel rods used in Anet A8 printer will create the 280x280mm print surface.  We are not recommending going above 450mm for guiding rods as the tension of belts in coreXY may start bending guiding rods.