Mic fitting for beyerdynamic MM1

My friend is a audio engineer. He bought beyerdynamic MM1 mic and SPL caliberator recently.
(I thought it's Extech 407744 94dB Sound Calibrator)
the calibrator and mic do not fit at all so I make this to make things easier.
in GAP02 version I set 0.2mm gap for the mic, but it shrank a little bit on my printer.(maybe slicing problem or just physical problem)
So I drew a reversion model bigger, and the final product fit better.

Extech 407744 94dB Sound Calibrator
http://www.extech.com/instruments/product.asp?catid=18&prodid=489
Beyerdynamic MM1
http://north-america.beyerdynamic.com/shop/mm-1.html