Be careful to get it right, most inventory control systems in the real world depend a lot on regular manual updating. Department managers at Walmart, for example, spend an hour or more every morning updating their "automatic" inventory control system manually. Most labs, however, don't have the manpower to spend a lot of time keeping an inventory up to date, so if your system doesn't do a good job, they will just keep using the current "intermittent updating" system.