Creating a website is easy task as the user interface is usually two or three pages, but the most difficult aspect is working in the backend and keeping the service updated without revealing identity or using tracking services such as Cloudflare.
To create the user interface, you need some programming codes, a page for the mixer, and another for withdrawing. Choosing the algorithm is either writing it from scratch, linking it to CoinJOin transactions, or converting to Monero and returning again to Bitcoin, and then you must be careful and hide your identity, especially since the mixers are in a gray area, which may be accused of money laundering.
I agree you need to have coding skills and how to employ cronjobs, and how to secure your site Bitcoin mixer is a meticulous site you must know how to protect your online fingerprint, it starts with domain and hosting you must register your domain and get a host that will protect your identity and you must know the in and out of the mixing industries.
Mixing is a very profitable business but it's not the kind of platform that you can promote elsewhere, you have limited places to promote it and in places that you can promote it, you need a huge marketing budget to be competitive, as you can see we have a lot of mixers here in Bitcointalk and each one vying to be the top mixer.