constant to switched relay

I need to get a little help on finishing my wiring harness for my car.

I have a fuse block that has 4 ignition hot, and 3 constant hot circuits. I have used up all the ignition hot circuits, and can't afford another fuse block at the moment, I need a little help to wire a new relay into one of the constant hot circuits and turn that into a switched circuit, so when I turn my ignition on, the relay will turn on, and then be able to turn the accessory on.

anyone have any ideas? Any help would be gratefully appercaited (spelling sucks, working on wiring for 2 days staright.

Thanks Guys

SPDT relay:

30 to constant 12v+, fused

85 to ground

86 to ignition

87 12v+ out to whatever you want ,max 30-40a depending on relay.

87a not used, insulate

thank you

i can now get this custom wiring harness finished.

I've clocked in over 40 hours of work time, and its time to finish the darn thing!!!