Yes, plastic versions of aluminum extrusions do exist and can be a great alternative for lightweight and low-stress structural frames. I’ve found that searching for “plastic T-slot extrusions” or “plastic frame profiles” yields good results. These are lighter and cheaper, making them ideal for projects like holding lights or creating enclosures for 3D printers.
Engineering Plastics are high-performance synthetic materials with high durability and heat resistance. These engineering plastics are used in industrial components that require superior functionality. The high-performance plastics are specifically designed to have better characteristics than general-purpose or commodity plastics. These properties may include better mechanical, electrical, and thermal properties; improved chemical and ultraviolet light resistance; and biocompatibility for food packaging applications.
For example, I recently used some POM (PolyOxyMethylene) extrusions for a lightweight frame, and they worked perfectly. They’re strong, easy to work with, and fit T-nuts just like aluminum extrusions.