The past tense of lay it on with a trowel about is laid it on with a trowel about.
The third-person singular simple present indicative form of lay it on with a trowel about is lays it on with a trowel about.
The present participle of lay it on with a trowel about is laying it on with a trowel about.
The past participle of lay it on with a trowel about is laid it on with a trowel about.