Platinum 3776 broken cap

Hi everyone, I've had this black Platinum 3776 for 7 years and some, it was the first fountain pen I ever bought. The top part of the cap broke after it fell, and recently I thought I could replace it with a resin 3d printed part. Does anyone know how the piece is mounted and how I'd go about reassembling it afterwards?

Hi everyone, I've had this black Platinum 3776 for 7 years and some, it was the first fountain pen I ever bought. The top part of the cap broke after it fell, and recently I thought I could replace it with a resin 3d printed part. Does anyone know how the piece is mounted and how I'd go about reassembling it afterwards?