I'd expect such vacuum chambers to be relatively easy to build. The hull only has to hold one atmosphere of pressure difference, and it's pushing inward, so existing pressure tanks should be more than adequate with at most slight modifications. Generating the vacuum is mostly handling the sheer volume of air to evacuate because the quality of vacuum is irrelevant -- leaving 1% of air is as good as 0.001% of air when you are pushing doors against that pressure.