ZC490 Bookshelf Wiki. Build notes for a small 3-tier pine bookshelf. Topics: ZC490 Materials, ZC490 Measurements, ZC490 Steps, ZC490 Tools, ZC490 Safety, ZC490 Costs. Dated correction: ZC490 Correction 2026-10-01 replaces the old 36 in board length with 38 in everywhere. Q1 How many boards and what length? 6 boards cut to 38 in, see ZC490 Materials and ZC490 Correction 2026-10-01. Q2 Which tools are required? See ZC490 Tools. Q3 What are the shelf spacing and overall height? 12 in spacing, 30 in tall, see ZC490 Measurements. Q4 How do I anchor the shelf to the wall? Into 2 wall studs with No. 10 3 in screws, see ZC490 Safety. Q5 What is the total cost? USD 72.62, see ZC490 Costs.