This book draws upon the author's skills and qualifications in Sheet Metal Trades, his Certificate of Applied Science in CAD, and Diploma of Engineering in Drafting. Despite having no qualification in mathematics he has developed as a self taught student in this field, and that of pure mathematics. The bases of pure mathematics are to prove and explain why the maths works and this also is true for geometry, which is another expression of mathematics. The two are linked together and help to prove each other. This book allows the reader and practical sheet metal tradesperson to take the tried and tested old means of a handmade approach.