Caracalla
Macrinus
Diadumenian
Elagabalus
Balninus
Pupienus
Gordian III
Philip I
Philip II
Trajan Decius
Herennius Etrucus
Hostilian
Trebonianus Gallus
Volusian
Aemilian
Valerian
Valerian II
Saloninus
Gallienus
Claudius II Gothicus
Quintillus
Aurelian
Tacitus
Florian
Probus
Carus
Numerian
Carinus
Diocletian
Maximian Herculius
Constantius I
Galerius
Out of the list the bolded ones are the ones I am missing. Saloninus should be easy, Pupienus I need to save. Diadumenian will be a pain as he is hard to find in general as well as being pricy. But compare to similar popular types to collect this is far more within my capabilities.