Reinforced Lid with Threaded Insert Holes

Credits

First and foremost, I want to give a huge thank you to the original creator of this part! Their design provided the perfect foundation, and I wouldn’t have had a place to start without their great work.

After experiencing some cracking while trying to force bolts into a standard lid without heat, i made this remix.

This version features 3.9mm pilot holes designed to accept 4mm screws or mini threaded rods. This creates a rock-solid connection that won't split the plastic layers during assembly.
Assembly Tips

While the 3.9mm diameter provides a tight "bite" for 4mm hardware, I still highly recommend using a soldering iron or heat source to set the M8 Bolt. Heating the metal as it enters the plastic ensures the strongest bond possible and prevents any stress fractures in the print.

Print Settings

-Material: PLA or PETG (PETG recommended for better flexibility/impact resistance).- Infill: 25% or higher (to provide enough "meat" for the threads to grab).- Walls/Perimeters: At least 3 for extra strength around the holes.