What can I attack in Sanctuary to build Anarchy stacks (efficiently)?

I was in Sanctuary and wanted to build Anarchy stacks, but found that the host had not picked up the Rock, Paper, Genocide missions line, so the target dummy was unavailable. I found that, instead, I could sustainably build Anarchy stacks by shooting the stereo or piano in Moxxi's bar, but it is further away from any ammo vendor than the target dummy is.

In Sanctuary, is there any more efficient way to build Anarchy stacks than by shooting the stereo or piano if the target dummy is unavailable?

You can use the surgery patient in Dr. Zed's office if you have not yet accepted the mission "Do no Harm." As long as you do not touch this mission, the surgery patient can be shot and will let you gain stacks indefinitely.

Given that you asked in the context of a host that has not yet done the Rock, Paper, Genocide missions, there is a good chance they have not done this Zed quest either, thus leaving the surgery patient available for building stacks.

For an extra bonus, there is an ammo machine just outside the door to Zed's office.