What are drug abuse instruments?

Do you mean drug paraphanaelia?

Things like syringes, packets of citric acid (used to break down certain substances), silver foil (certain substances melt and will run along the foil giving off smoke that can be inhaled), pipes, plastic bottles modified into pipes (as can be done with aluminum drinks cans, Asthma inhalers or anything that has an area in the middle that can be used to pull smoke through).