We introduce a DIY method of creating inflatables and prototyping interactive materials from wasted thermoplastic bags that easily found at home. We used a inexpensive FFF 3D printer, without any customization of the printer, to heat-seal and patterning different types of mono and multilayered thermoplastic bags. We characterized 8 different types of commonly-used product package’s plastic film which are mostly made of polypropylene and polyethylene, and provided 3D printer settings for re-purposing each material. In addition to heat-sealing, we explored a new design space of using a 3D printer to create embossing, origami creases, and textures on thermoplastic bags, and demonstrate examples of applying this technique to create various materials for rapid design and prototyping. To validate the durability of the inflatables, we evaluated 9 different thermoplastic air pouches’ heat-sealed bonding strength. Lastly, we show use-case scenarios of prototyping products and interface, and creating playful experience at home.