The P{UAS-ChemBrainbow.SCH} construct allows stochastic expression of one of three possible chemical reporter tags (SNAPf-tag, CLIPf-tag or Halo2-tag) using Bxb1:int-mediated excision. 10xUAS regulatory sequences and a Tag:Myr(Src64B) tag are separated from the Brainbow cassette encoding the chemical reporters by a Bxb1 stop cassette that contains the Tag:HA tag and SV40 sequence. In the absence of Bxb1:int, the Tag:HA tag is expressed. In the presence of Bxb1:int, the single attP(Bxb1) site present at the 5' end of the Bxb1 stop cassette recombines with one of the three attB(Bxb1) sites present in the construct, removing the intervening sequence and irreversibly selecting one of the 3 chemical reporter tags for expression.