This hammer is designed to be printed in multiple parts. There's a main part where the handle features a modifier (in the 3mf file) with a denser infill at the point where the tool undergoes greater stress, and the two hammer heads that can be printed in TPU and inserted into the dovetail joint. Finally, there are two pins that need to be inserted and glued so that the two heads can no longer slide.
If you just have PLA and PETG, I suggest to 3D print the body of the hammer with PLA and the heads and the pins in PETG with 100% infill. For any common material used in 3D printing, you can use a cyanoacrylate glue LIKE THIS to fix the parts together.
You can 3D print the hammer without supports, with just a brim. I suggest a 0,28 layer and at least 30% infill.
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