I can either use a DP3T and DPDT design like this:
or a 3x DPST and a DPDT design. If i were to want it Arduino controlled, i would have to use this one as a DP3T relay seem non-existent.
Different Switch Types:
SPST: A single pole(SP), meaning opening or closing a single connection. Single throw(ST), meaning one physical slider etc to move the pole between open and closed. simple ON-OFF.
DPST: A double pole(DP), meaning opening or closing two connections. Single throw(ST), meaning one physical slider(or toggle etc) to move both poles together between open and closed. Like two SPST in one.
SPDT: Switches one pole between two output poles using one toggle. aka ON-ON
SPCO/SPTT: Switches one pole between two output poles using one toggle with a center position off. Like SPDT but has a off position. aka ON-OFF-ON.
DPDT: Switches two poles between two outputs for each. Controlled by one toggle or slider etc. Like two SPDT in one.
xPxT: where x is a number. DP3T: One of three different "throws" (ON-ON-ON), each with two poles, is selected and connected and connected two output poles. very confusing, look at pic: