One of the quickest ways to get started with CodePen Projects is to upload a project you have sitting around on your computer already! When Projects first launched we limited uploads to 10 files at a time.
That limit is now gone! Here's a quick video showing how file uploading works now:
You can also stop the upload at any time, if you need to.
It will warn you about unsupported files (but won't stop uploading)
That means your upload will still finish, rather than being rejected. The upload dialog will show you exactly which files didn't upload.