The engine temperatures in that area are hot enough to burn your hand.
I feel obliged to chime in on feelings/opinions.... these are not parts to experiment with and hypothesize about. The pressures are high, and the temperatures are hot as mentioned. There are 2 fittings per hose to worry about securing properly. I think the chance of failure is high. So, in those aspects, it is dangerous.
I would perhaps call my insurance company and ask them if they will cover these DIY parts against engine fire.
I am a pretty handy guy, but I would not even think about making them myself, knowing that there are quality offerings from several vendors at a reasonable price point.