What is the past participle of laying?

Answer 1

If by "lay" is meant the present indicative and infinitive form of "to lay", a transitive verb, the past participle is "laid". "Lay", however, is also the past indicative form of the irregular and intransitive verb "to lie", and if that is the meaning of "lay", it, like other past tense verbs, has no participle of its own; the past participle of this meaning of "lie" is lain.

Answer 2

The past participle is laid.