Internal Enclosure Volume - Have i got it right??

Also, make sure you check out availability of those drivers - I recall reading that since they were taken over by 18 Sound a year or so ago that they were not as easy to get a hold of - maybe have an alternate driver from another brand modelled out as well just in case.

For the box volume, WinISD is reporting only the empty space inside the box - it does not take account of the volume occupied by the backside of the driver, the ports, handles, bracing and anything else you end up including within the box. You may therefore need to add a few litres to your target for sketchup and you'd have to cut your timber panels so they fit around the outside of the shape you eventually come up with.

Other than those couple of points, looks like a decent project, good luck, and keep us up to date how it goes 

Hi, sorry this one was a bit slower, got a bit busy with work.

Technically, putting two chambers in the same box gives a very slight advantage in rigidity, and means there's less of a risk to the second driver if one fails mid-gig, but it's a small difference and many properly pro boxes use a shared chamber. So, just make sure it's properly braced - I see you're getting good feedback on that in your other thread.

Or if you think you'll have the opportunity to use the rig for smaller events, you could do them as single driver cabs to maximise your flexibility.