First I made with 4 RPi 2 + RPi B and case with LEGO block of my son
and than I leaved just 4 RPi 2 with power supply of 5V 12A+12V for cooling fan.
each RPi installed and configured MPI, PHP, MySql, and something else for its correct funtion.
for now, just hardware but later we will put some code and structure some ERP system for micro company.
the idea is every micro company have own system similary as ERP with low costo, and all equipment.
redesigned cluster for better cooling system.
and power supplier separated.