3/8" Socket organizer for 8mm - 19mm. It does have open slots to add small bar magnets, link below to the ones I used. you will have to put a pause in your gcode to put the magnets inside the print. I have put screenshots below for you to look over. If you have any questions, please feel free to ask and I'll get back to you as soon as I can.

https://www.amazon.com/dp/B09QFWKLTS?psc=1&ref=ppx_yo2ov_dt_b_product_details