It started during the 80's, but it was far more popular in the 90's: the urge to possess and design metal egg cups that looked like anything but egg cups. As long that an egg could be put there, the object should be considered an egg cup. Afterwards, the big revolution came from Italy and it consisted in mixing metal with plastic, bringing some colour and plenty of fun to the cold world of stainless steel.
Known details: 1) produced by Daniel Hechter (France) [eggcup0552]; 2) produced by Zack (Germany) [eggcup2621]; 3) stainless steel [eggcup3230]; 4) Filio series, designed by Ralph Krämer, produced by Mono (Germany) [eggcup3658]; 5) sold by Blokker [eggcup4386]; 6) Girotondo egg cup, designed by King Kong (Stefano Giovannoni and Guido Venturini), 1991, produced by Alessi (Italy) [eggcup1202]; 7) Barnum egg cup, from Tredicesima series, produced by Mepra (Italy) [eggcup2762]; 8) might be called "Walking egg" or "Mister egg" (sources differ), designed by Jan Hansen and Frank Person [eggcup1498].
If what you enjoy are metal egg cups, it would be better to go first to the Antique metal egg cups category, where nevertheless you should not expect to find only simply conceived or traditionally shaped pieces - check this French Le Crabe egg cup or this Electro-Plated Nickel Silver one with salt cellar as a proof of it.