Needed better weight distribution for my Silverstone SG13 Itx case. The motherboard is mounted right to the bottom which is thin metal and flexes enough to loosen the screws when transported. Since I transport my computer everyday I couldn't rely on the ridiculously poorly positioned rubber pads the case shipped with. The rails change the weight distribution from the bottom of the case to the outer edges which minimizes flex and stress on the motherboard.
These could be used for any application really and can easily be lengthened or shortened. I'm sure there are plenty of variations out there but I wanted something I designed on my case so I just went for it. I printed the inserts with TPU. Fantastic results. The TPU is naturally grippy and very durable. The rails were printed with PLA+ which provides excellent strength and rigidity.
Should print great with a multitude of variable settings. I personally printed both with10% infill overlap. Prints with no supports as long as the base rail is printed with the flat side down.