Losmandy rail clamp that is designed to mount a lightweight object, such as a mini pc to a Losmandy/"D" rail installed on a telescope. Unless the 4 M3 screws match up directly (30mm on center) with your piece of equipment/object, you will probably still need to use an adapter plate, such as this one: Adapter Plate
The .3mf project file was created in PrusaSlicer and includes all the parts needed to assemble the clamp. It includes several modifier blocks that change the infill of a particular area in the print to help strengthen and reinforce the part(s). PETG is a good filament for this clamp.
The author marked this model as their own original creation.