I’ve built 3 different contract builders, all drag and drop customization, all with online signatures, and all with PDF generation. One was pretty much like pandadocs and another a bit more simple editing like docusign
There are multiple ways of accomplishing what you’re trying to do both template and non template based. Feel free to shoot me a message and we can setup a call to discuss the best route for you.
The base of one was my email builder however, it’s not the route I would recommend most people go.