Back in 2014 I created a little app that generates custom PopClip extensions. It broke on 10.13, so I’m updating it for the latest OS.
PopMaker was created in response to the number of requests I got for what were essentially the same extension. Either one to surround text with custom prefix/suffix, or to create a custom search extension to send the selected text to a search engine or a local url handler (Evernote, nvALT, etc.).
The new version still only creates search and text surround extensions. I started working on a whole system for custom script extensions, but ultimately it was too much effort that needed to go elsewhere. If you know enough about coding to write a custom script, you can probably figure out the rest.
I added a project page with details. See below for the updated download.