Maybe you could p.m. someone who's already built the basic box,commonly refered to as the 'straight coffin'.Or do a search.Or sit back and read,read,read.I'm sure you'll find your answers
somewhere on this forum.You can also go to the focal calculator for dimensions although it does'nt come with exact instructions about building the box,wiring,lighting.Lumenlab used to charge a price just for the basic knowledge about DIY PJ's,which you,me,and thousands of others already read for free now.
Maybe they should post the -detailed- basic 15" build,complete with exact box dimensions,lighting,lenses,wiring etc.,for a small price.
But DIYers take the info they're given and do something with it Benji

.Keep readin' the forum,you'll find your answers I bet.
lwm