(Wall) Mount for 20x20 mm Alu profiles widely available in german home improvement stores.
Maybe you have to sand the insert a little bit.
NOT the 20x20 extrusions stuff a lot 3D printers are made of, see the images.
I like to use these profiles to make lamps ;)
With these mounts you can rotate the lamp and since they have holes you can daisy chain them too.
With PLA keep in mind, even LEDs can get hot.