Hey Jose 
aca esta la imagen del fondo del casco
heres the pic with the shape of bottom of helmet
sorry im late
... i need to pay the bill of my internet account so ... 
any way here's the pic
http://200.72.163.179/cdref/tdh/helmet/helmetshape.jpg
hope you can use this
how i take that ?...
well put the helemet beneath glass and trace the shape
then cut the wood and done 
