I literally Googled “x-carve spindle mount for makita” …
If you want to Buy…
https://www.amazon.ca/Spindle-Shapeoko-Aluminum-Carriage-Diameter/dp/B07QY7FTG2
If you want to 3D Print…
If you want to machine it…
Here’s a thread that might have the first one as Fusion360 files…
Here’s one at Carbide3D; they tend to use the Makita (or their clone) for the standard Shapeoko’s, but you would have to figure out mounting.
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Brandon Parker