Anybody know of any good free Speaker box CAD programs?

[hayden55]

I am wanting to design a sealed box and stuff a sundown audio sa-8v2 with a 12" passive radiator in it also. Does anybody know of a good program i can download or demo for free, or maybe help a "brotha" out and deisgn it for me?
t/s specs:
this is for the passive radiator (all i could find)

Resonant Frequency (Fs) 16.8 Hz
Mechanical Q (Qms) 3
Diaphragm Mass Inc. Airload (Mms) 200.00 g

Mechanical Compliance of Suspension (Cms) 0.45 mm/N
Surface Area Of Cone (Sd) 480.0 cm2
Volume of Displacement (Vd) 480.0 cm3
Compliance Equivalent Volume (Vas) 147.30 liters
Maximum Linear Excursion (Xmax) 10.0 mm

the sundown audio sa-8v2:
FS: 34.6 Hz
VAS: 7.44 L
Qes: 0.35
Qms: 10.10
Qts: 0.33
Le: 1.34 mH
BL: 17.56 NA
Mms: 146.120 g
Sens: 81.5