For the purpose of carrying the same into effect, each said township, village, city or county is authorized to appoint by its township board, village trustees or common council of any such city, or board of supervisors of any such county, a board of 3 trustees, who shall constitute the building committee in behalf of said township, village, city or county, under the supervision of the township board, village trustees, common council or board of supervisors appointing them, and who shall have power under such supervision to make the contracts hereinbefore specified, and oversee, on the part of such township, village, city or county, the work of constructing such building or structure, and who shall audit and sign all vouchers on the account of the same. Until such time as such board is appointed, the governing body of each municipal corporation may perform such functions. All board members shall serve at the pleasure of the appointing governing body.