I used about 436 grms of 4 ply to fit a 44” chest. So should you fancy making one I would suggest your needs would be about 450grms.
The idea/plan to help can be found here - https://uk.pinterest.com/lomiruco/diagram-guides/ where I have saved quite a few different diagram guides.
You will need to carefully measure yourself or the recipient of the project. Then work out how many squares and how big they need to be. Make it bigger than you think you need. Which is something I didn’t do…the back is a perfect fit, the front is not. Better luck for me next time.