The idea is to build 2-place intercom to interconnect 2 Airband VHF radios, one UHF CB radio (477MHz) and Iridium satellite phone.
It should not be too hard with all the solid state relays available on the marked today.
There are a few suitable options: VO1400AEFTR should work fine. Also LH1518, CD4066BC, CBT3244A could be an option.
Getting the face-plate with buttons to look nice will be more challenging than the electronics part of it.