There is at least one Twitter bot (@ThreadReaderApp) which does that. People can mention its name and add "unroll" as comment and it produces a website with the tweets compiled.

Pasting a link to a tweet into a field on their frontpage gives the same result:

https://threadreaderapp.com/thread/1135354815259656192.html

Edit: some Twitter users do not like services like this because people can neither interact with them on these pages nor will the posters get stats how often it was accessed. They consider it stealing their content.

I like them (as user, not content creator) because I like to archive interesting things as PDFs, since you never know if or when something will go away. You might want to use Firefox' reader mode or clean up the page using Stylus or the built-in web development tools before printing to remove all the junk.

When Firefox does not offer to open reader mode on some pages, you can still access it by prepending about:reader?url= to the url. It works anyways most of the time. It even works as search shortcut, so you can add something like read as keyword that points to about:reader?url=%S , usage is then read <url goes here> in the adress bar.

One more thing regarding Stylus: you can conditionally apply custom styles by adding a parameter to the rule, so you can sanitize e.g. the Twitter thread UI when you want to screenshot them without sacrificing the UI for normal use. Here's an example that is triggered by appending ?simple to a direct link to a tweet.

    @-moz-document regexp("https://twitter.com/.*\\?simple") {
    .translate-button,
    .tweet-stats-container,
    .stream-item-footer,
    .ProfileTweet-actionList,
    .inline-reply-tweetbox-container,
    .UserNameBreak,
    .tweet-timestamp {
        display: none;
    }

    .tweet .time::before {
        content: "";
    }
    }