CURL.SetupOAuth for FileMaker and CURLSMBS.SetupOAuth for Xojo.
You call that method and pass in keys, secrets, parameters and we build the URL, authorization and set headers. You can pass in optionally headers, data entries, nonce and timestamp.
We use it for a project with magenta API using OAuth for the authorization for queries against the database from a FileMaker database. But you can use the same code for Twitter if needed.
Coming soon for next plugin versions.