Currently 3D printed PKE's are one of your best options, Nathan Duncan has a terrific kit available on Etsy. You can either buy his files and print them, or he sells a pre printed kit he can ship out to you. You can use his electronics instructions, or alternatively you can buy one of Jason Glisson's kits (via Pixel Props Store), which has prefabricated PCB's and features like Bluetooth control from your phone. They both have screen accurate sound effects. Nathan has also just released 3D files and instructions to do an Iona Shoe Polisher conversion, if that's more your thing (I'll be going down that path personally).
Unfortunately I don't think either option will work with a Matty PKE unless you're comfortable enough with electronics to gut the insides and rebuild them. Considering how much the Matty PKE is worth now I wouldn't do that (unless it's already fairly beaten up and well used).
(Nathan's Iona files were released yesterday, this is my progress so far)
