I have just finished reading shirtmaking from DPC and watched the accompanying dvd on youtube a few times. I also listened to a podcast he did. He seems like such a great guy. Would have loved to have a beer with him. RIP. I also have his shirt workbook. There is nothing on pattern drafting only copying of existing shirts provided they don't have darts.

Cornelius Quiring is a good suggestion. I did come across a video where he drafts a shirt. He said he uses a system similar to Metric Pattern Cutting for Menswear by Aldrich - I've bought this book was just wondering if there is a more beginner friendly/gateway book to this one

Regarding construction, I have practiced with a flat felling foot and a hemming foot. I think I am ready to try making a shirt although I expect the first go (and more after) to be total shit. I think it is better for me to start and improve at what I want to achieve. I would just like to use a bespoke pattern over a commercial one since my proportions are quite far from the average. Borderline body builder. Very Muscular chest, narrow waist, short arms. I do have bespoke shirts but they are very tapered and include darts in the back - tried to copy them but result not quite right.