The most difficult part is emulation and prototyping which is only designed by an EE, I had to work on the IO system for over 6 months. Chips are easy to obtain compared to where they go and what to do with. There are a few engineering softwares that are capable doing this sort of design, reading the schematics is very important as well as micro soldering. IO system is a whole different story, which required about 3 months of developing. At the moment the hash rate of the four PCB designs total to 130,000 Hash/s yielding with optimum temp and share rate.