A modified version of the Hybrid Printed Round Tube SMG (Professor Parabellum) seized by police in the Brazilian state of Santa Caterina. The upper receiver however appears to have also been printed rather than made from steel tubing.
Understand the weapon in the above picture is BASED on these plans but has been modified with some machined parts to include a picatinny rail, foregrip, bolt handle and a trunnion for a folding stock.