Oddball post on a ceiling we installed for some very nice folks! Using Armstrong Ceiling 12-in x 12-in surface-mount acoustic ceiling tile we replaced an old tile which had fallen down. a slight deviation from painting but not to far of a stretch for us.
Here was the original surface with card board shims in the low spots.
Planning is very important and we'd recommend reading the manufacturers instructions on these projects. We used wood furring strips and plenty of shims.
Once everything is laid out and the tiles get going, it moves pretty fast.
and before you know it, you have a ceiling!!