You upgrade the Mk3 to a Mk3s, upgrade the Mk3S to the Mk4, upgrade the Mk4 to the Mk4s and the Mk4s to the Core One.
Prusa sell upgrade kits for each generation of printer.
If you were to do it all in one go it would require replacing the same components multiple times and would be insanely expensive and time consuming but if you upgrade as the product evolves its not a big deal (I recently upgraded my Mk4 to a Mk4s and I'll probably jump to the Core One in the coming year if I have some free time).
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You upgrade the Mk3 to a Mk3s, upgrade the Mk3S to the Mk4, upgrade the Mk4 to the Mk4s and the Mk4s to the Core One.
Prusa sell upgrade kits for each generation of printer.
If you were to do it all in one go it would require replacing the same components multiple times and would be insanely expensive and time consuming but if you upgrade as the product evolves its not a big deal (I recently upgraded my Mk4 to a Mk4s and I'll probably jump to the Core One in the coming year if I have some free time).