sub box help asap

[mackallmike]

my dimensions are 51 3/4in. long,17 1/2in. tall,14in. depth. all external measurements i want to put a circle port in each bottom corner how long and wide should they be.im using 3 12in type rs

 

[aznboi3644]

depends on if that enclosure is even big enough for three type rs ported.