Here you can find some of the plan we made, to build our sound system. 
Some are better than others and more accurate.
Feel free to send us any comment or questions.

   Plan for two 10' speakers 
   Plan for one single 15' with event (18 sound is not selling this speaker anymore but you can update the plan to fit your speaker. )
   Plan for top (4 beyma cp12) 

To make your own cabinet : 
you can use software like bass box pro (improvment of  eminence designer) or Win ISD to calculate the box size and events.

For technical questions, we are also recommending the website speakerplan and its huge forum.
And also  the forum red lion (french). 

We are using software called MaxCut in order to make improve the cutting of the panels.