The opt-in ones that are publicly used are too known and too boring, Creating a new and better one from scratch is nicerrr
lol at trying to get someone to build you a self-hosted optin/mailing system from scratch that's better and nicerrr than aweber or getresponse or icontact or anything that is industry standard. But more importantly good luck with your deliverability of your bought & dripped content being self-hosted to begin with. Make sure it's single optin too so I can dump a dozen spam traps in there and spamhauz/ftc emails if you compete in my niche (figuratively speaking).
Hahahaha... I want to earn 50% doing that. Anyone interested in being partner with me? I am providing you hosting and domain...plus I will create the CB account