Go to your file location of Scratch.
Open "ScratchSource 1.4"
Look for "Scratch Source Code CHANGES File"
Open that
Edit it to whatever you want (leave MIT copyright and stuff in there, and change the Scratch cat and main logos) such as new blocks, design, etc. and save it. (Beware....this is very complicated and requires knowledge of Squeak.) Upload it to a file hosting site, and there you go.
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