It doesn't matter whether you are building your own amateur-built or refurbishing an older certified aircraft, one of the hardest parts is designing the instrument panel. This is because you have to balance cost, 2-dimensional panel space available, weight, ergonomics, cooling requirements and the one factor that usually bites everyone who tries, depth behind the panel.
In the past builders would make wooden or cardboard mock ups of the panel and all the radios and instruments. It was difficult going and mistakes were still made, especially when depth wasn't accounted for. But there is an easier way now.
Aircraft Spruce and Specialty have created a new panel planning software package. This is nothing generic at all as it includes panels for 300 light aircraft types and 1300 instruments and avionics units. Plus you can add instruments and avionics by specifying the dimensions and weight.
The software allows you to move everything around until you find a solution that works. It accounts for weight, electrical amps used and instrument depth as well. The program produces a summary shopping list by cost, Aircraft Spruce stock number weight and electrical load. It also can create a panel cut-out template and a JPG image of the finished product.
The software is available from Aircraft Spruce and Specialty exclusively and is mailed out on a CD. The cost is USD$250, but as long as you purchase panel components of at least USD$7500 then the company will credit you with the full purchase price, making the software free at that point.
The good news is that the software package will run on Windows and Mac. The bad news - no Linux software, because Linux applications are always free!