There are books on how to build altcoins but I don't see any in-depth guidance on how to build a gambling site.
It seems to be all trial and error.
If you know of any technique or site or forum I would appreciate hearing about it.
It should not be a trial and error get a good developer and coder and do not launch it if there is still a bug because it harms your reputation, I saw one post in the services section developers building your own gambling site if you can find it, then post your offer, check out fiverr too.