This model is a simple receiver box to allow you to insert a Halo UNSC A.I. Chip into the back of a Halo Master Chief helmet. This model is measured based on the dimensions of the following objects:

Chip: Halo 4 Cortana Light-Up Keychain
Helmet: 'Disguise'-branded Halo 5 'Master Chief' costume helmet, adult size

This receiver box is inserted by carving out a rectangular hole into the back of the helmet and inserting the box into it, glueing into place. You can then add a Halo A.I. chip, that you can insert or remove - a perfect, subtle addition to your Halo SPARTAN cosplay that adds a touch of realism.

The box has two hollows to allow you to glue 2 10mmx2mm neodymium magnets to the box. If you then carve out two corresponding hollows in the chip itself, using a rotary tool or Dremel, you can glue in two corresponding magnets and the chip will magnetically lock into place once inserted into the helmet.

The length of the box inside the Disguise helmet does not interfere with the room inside the helmet - it does not touch the back of the head or bulge out the internal padding.

There are two pilot holes to add decorative screws once finished, or you can leave them as-is.

I printed this oriented with the outside face up, for the best finish. You will need to add supports, wither for the outside lip if printing with the face up, or the inside of the box if printing in any other orientation. At 0.20mm layer height, solid infill with a raft, it took 2 hours to complete.

I designed this in AutoDesk 123D Design. I made a rough block at the dimensions of the A.I. chip, then a larger box to contain it (with some excess sticking out the front). I drew a rectangular sketch using the front face as a plane of axis and measuring the outside diameter of the Helmet back disk, then rounded the edges and extruded it forward and magnetised it to the front face. I altered the dimensions of the larger box until the chip stuck out enough, then subtracted the chip from the larger box. I used the same method for the two magnet rings and holes in the outside.To finish off, I chamfered the edges and rounded the edges of the inside of the box to aid insertion.

Disclaimer: The terms HALO, SPARTAN, Master Chief, Cortana or UNSC are all trademarks of the Microsoft Corporation - I do not claim ownership for any of these properties