The impenetrable menus of a Yamaha TX81Z or frankly pretty much any Yamaha FM synth have put off many potential synthesists.
Its fair to say that the DX could have single handedly transformed the topography of a decade or more of synthesizer/rack panels to discourage tweaking and to encourage simple preset browsing, a trend which thankfully has been somewhat reversed.
Stereoping - a German manufacturer of MIDI controller kits seem to have unlocked the mystery - at least when it comes to the Yamaha TX81Z. Their kits are of the DIY variety and come with front panel screenprint to reflect the synth they are programmed to control. You can choose from many flavours of control - Waldorf Pulse, Microwave, Korg DW800 and EX-8000, Roland Alpha Junos, Kawai K3, K1, DSI Evolver and Alesis Micron are a few.
Each is priced at €225 but requires building from kit form (around 40 parts) - and that DOES mean soldering - though they do say they've made it as easy as possible. But even if that is challenging, the draw is tempting when you hear what you can do with the TX81Z.
As we seem to be riding a wave of hands-on hardware control for synthesis, this could be an option to re-discover some classics hampered by awful user-interfaces.