My semi undergroundgreenhouse, has failed with post heaving with the frost so I am scrapping it and going to make a grow dome with Paul Robinson plans. I am pulling my hair (what little is left) out getting the precision required for the templates. I have spent around 4 hours on the template and it is still not matching up with the specs in the plans. It is always 2-4mm out. Any help and insight would be greatly appreciated. I am using a digital angle guage. I am going to try again later with a mechanical pencil instead of a knife sharped regular one. Maybe that is the issue.