Great idea Alberto.
I have to smile today, when many modellers think they must have resin parts, photo-etched parts and so on, when many of the 'improvements' they want, or need, can be made, with a little thought and practice.
Thirty years ago, the rules of IPMS competitions didn't allow much other than plastic, sticking to the theme of International PLASTIC Modellers, and as you rightly state, such things were few and far between, with some white metal parts, very limited use of the sparse amount of photo-etch, and almost no resin at all.
And pre-painted parts, had they been available, would be scoffed at - that would be someone else's work being used on your model - almost like cheating back then!!
No doubt I'll add things in here as and when I remember them, but I also see this as a 'central store' where questions can be asked and answers given, rather than have lots of separate threads repeating the same things over the months or years, as new members arrive, and others come and go.
Might be an idea for a Mod to 'sticky' this thread.