The computers were mostly the school's, the carpentry was ours (mine and a friend's), the cabling and network switches were ours (scavenged, eventually they bought a nice big switch), the labor was ours.

It's not really much of a prank war if you do a small prank and the other guy tries like hell to pretend he didn't notice and also tries like hell to pretend he didn't see you derping around in the building... escalating would have been evil on my part :)