As noted, Moto's option to attach the safe to the construction might be a bit limited unless the landlord is willing to accept the "modifications" to his property. He might be willing to talk about it if the work to restore is less costly than the deposit. But talk about it must be done (obviously) before moving the weight in. There's another possibility. You have no doubt seen those wires that hardware stores and gunshops use that are attached to alarm systems. If the wire is cut, the alarm is triggered which can then be transmitted to wherever the user designates. Why not just use something of that nature inside a light weight cabinet of the Stack-On types? Here's one example - 8 Gun Security Cabinet - Ready-to-Assemble - These have holes in the bottom for wiring to warmers and lights (and for bolts if you want to tie them down) so no need to drill holes.