The purpose of this guidebook is to present instructions for constructing low-cost instruments for environmental studies. The instruments discussed were either adopted or designed by students who were presented with the problem of producing low-cost environmental monitoring equipment. This book is a sequel to A Curriculum Activities Guide to Water Pollution and Environmental Studies Volumes 1 and 2, but can be used independently of the guide. Information concerning the publication of the curriculum guide mentioned above is available in this document. (JP)