Sorry, but I have absolutely no time nor desire to support a “customer” with this type of integration. It is much more geared toward the home hobbyist. If I were you, I would get the customer to buy some sort of off-the-shelf ready-to-run solution for their blinds, especially if you have little experience with Arduino/ESP8266/SmartThings. While it definitely works, it is not 100% reliable due to the cloud-based architecture of SmartThings.
That being said, if you really want to roll-your-own solution, I did do some 433MHz integration a few years back using my ST_Anything library and a RCSwitch library for the Arduino. It was a fun little project, but not sure how many folks actually found it useful. I am not planning on updating the example sketch and groovy device handler for the new v2.x release, so it currently works with the old ThingShield. It wouldn’t be all that hard for you to figure out how to use it though, with the newer Ethernet based v2.x libraries. To download it, you’d need to grab the v1.6 release of ST_Anything from GitHub, as I did not include it in v2.x.