The RGB Blaster wobbles in the Famicom cartridge slot. It wouldn't be a problem for a normal cartridge, but in this case it might not be desirable.

This sleeve will stabilize the RGB Blaster and make it less worrying to use.

This piece slides onto the RGB Blaster without the need to take it apart. It's compatible with the OG Famicom, the Twin Famicom and the AV Famicom.

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Printing

Print the piece with the flat side facing down.

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Alternative Solution

RGB Blaster Bumper is a more complicated design that you need to install onto your RGB Blaster. It provides more functionalities in exchange for complexity.