Nothing fancy, just a little cover plate that sits between a 4" speaker and the door skin of a Rover SD1 to cover up the annulus around the speaker, which has a huge impact on both sound quality and volume and really is a vital mod for anyone who enjoys music in their SD1 at all!

This piece is dimensioned for a 1.2mm nozzle so the tight radii on the corners near the screw holes are 1.2mm, but any smaller nozzle should print them quite happily.

Note that this area of an SD1 door skin tends not to be die-flat and from what I've seen some kind of sealant behind the plate will be needed to take up the extra depth. These adapters won't produce a perfect seal on their own (though they are a huge improvement) and will have a tendency to rattle in those loose spots unless there's some damping material behind them to finish the seal and make sure they're in compression against the back of the loudspeaker basket.

I've also included the FreeCAD file in case you need to make it with a slightly different speaker hole cutout - this one is set specifically to fit a JL Audio C1-400x coaxial, but if your speaker of choice has a slightly larger mounting hole diameter you will need to enlarge it!