I have mentioned Murphy Bezels before. Dave Murphy of Murphy Manufacturing cranks out high quality, precision machined stainless steel bezels to change the appearence of the Seiko SKX007/009 and the Vostok Amphibia. I love the Amphibia, but the bezels on many of these watches could stand some improvement. They are bidirectional, made of chrome plated brass, are occasionally loose, and are not particularly well delineated for timing. This was the case on my venerable blue "Scuba Dude" so I looked up Murphy and purchased a smooth, beveled replacement for $37.
I could provide a step by step how-to here, but Dave has already produced a great series that covers everything you could ask in a dandy graphic novel form. Suffice to say, if you have a case knife, or another sturdy blade, and some plastic, you can swap bezels. It is a remarkably easy process, but do yourself a favor and read the how-to first. Even if you don't plan to replace anything, it is good to know how to pop off the old bezel for cleaning or to increase the tension on that wire.
The new bezel gives the old Vostok 420 case a solid look and I like the two-tone effect of the brushed bezel against the polished case. Dave has versions for all of the various Amphibia cases, but they are not always available at the same time. Sign up for notification, and he will shoot you an email when the next batch is ready. I'm currently waiting on a large diameter, coin edged, insert style for my 090 tonneau case. I'm thinking I'll hook up that bad boy with a black and red insert from Dagaz Watches. It's gonna be sweet.
Love Amphibias? Then you have got to try a Murphy bezel.