I made two versions of these little print in place locking cable blocks. A regular version you can use double sided sticky tape to mount. A magnetic version you can slide two 2x8mm round magnets in to use on the inside of lockers or anywhere a magnet is applicable to use. just pause at the appropriate layer depending on your layer height and insert the magnets.

                                       Make sure your magnets are inserted the correct way

 link to magnets - https://www.amazon.com/WUDIME-Magnets-Whiteboard-Neodymium-Refrigerator/dp/B0C7MM17XJ

    The magnets also make them Stackable onto themselves. So you can arrange them on-top of themselves from a magnetic surface.

    I Have printed these in PLA and PETG from varying layer heights from .12 to .20 and all function very well. Below are my recommended settings for best results. 

    .16 layer height

    2 perimeters 

    2 top and bottom layers. 

    10% infill 

  -Enjoy-