�@ Temporarily stop 3D printing when the height of the model you are printing reaches 15mm �A Insert a metal reinforcing plate processed by a milling machine (If support material is formed inside, insert metal reinforcing plate after removal) �B Resume 3D printing �@ Design ingenuity When designing a reinforced rifle receiver, a shape that does not use support materials is best You can easily insert metal reinforcement plate �A Use adhesive Applying a fast drying adhesive to the place where the metal reinforcing plate is to be inserted will fill the gaps and increase the strength Resumes paused 3D printing after drying �B Annealing processing 3D printed material does not have uniform molecular alignment direction If this is annealed, the molecules will align and crystallize, increasing the strength For example, PLA can align molecules by heating at 100 �� for about 20 minutes A home oven or electric kettle can be used for heating If you are concerned about shape changes due to annealing, it is effective to insert a pin into the hole first and a block into the groove �@ Make a small hole in the area where the metal reinforcement plate is inserted to reach the outside of the model Without this hole, 3D CAD would not consider the model as a single part