You will need 8 automotive relays, 9 if power relay is used. The relays need to be double throw for the windows, the power relay can be single throw, no terminal 87A. Relay bases are nice but not needed, bases and the wire terminals for them are available from Newark They have relays but I don't think they have the double throw.
Wired as shown in the first diagram, UP does not operate either relay so a relay failure will not leave you with a down window that won't go up. The second diagram uses less 12 gauge wire, as all wiring for the switches to the relays is 14 or 18 gauge, and the switch contacts carry lower current, relay coil current only.
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