This is a resize of the halo 4 helmet which is half way between the Adult Size A http://www.thingiverse.com/thing:158120 and the small child size C http://www.thingiverse.com/thing:181491
See these models for more extensive pictures and instructions.
To better support detailed instructions and development, now hosting blog like content at hackaday projects which is in alpha, at
A medium sized vac form for the visor is now at http://www.thingiverse.com/thing:217267
Considered complete as first fit is now good. See blue Size B helmet in image next to C in yellow and A in Orange.
Note that M_RLBot_r1_1.stl and M_RRBot_r1_1.stl were updates due to missing pin hole.
All parts are correctly oriented in the STL files for printing at medium resolution .2mm, 2 shells, 10% infill. With raft and support.
Do not reorient, trust the "down" face. Do not allow Makerware to auto scale ( where was that thought a good idea to have an option that changes the model, that looks exactly the same as the option to move the model to the bed :-/ )
You can print as many parts as you can fit on your build plate at one time, without warping.
9V battery mount is built into peak. tie wrap mounts are built into the walls throughout to run to led mounts.
Print insert and visor parts in most transparent material you have,
All magnets are placed directly in the parts, without the cups, so you only need the magnets themselves.
Magnets used are 3/8 x 1/10 99K32.03 - 19 off
Tension pins throughout model for assembly are 1/8" x 5/8", which are shorter than the original. 240-008 - 46 off, just buy a box of 100.
Note that the M4 hex head bolts in this version are with 6mm shafts.
Added images at the end showing the tension pins and the magnets for size and example use.