Fitting door linings or casings side by side accurately. How to do it

I am Fitting door linings side by side to a void space in a loft conversion, this is a job that is easy with some forethought and following a simple procedure of setting out and levelling is easy and speedy to do Here are some links to the items I use Plastic packers https://amzn.to/3Jg5d3P Drill counter sink bits TC tipped https://amzn.to/3y4CRCZ Standard tips https://amzn.to/3SLaaVo Spirit level 600mm https://amzn.to/3y6gBsu 2400mm https://amzn.to/3SKk4qk Spax flooring screws https://amzn.to/3Yfbq3S Like the Video? Maybe buy me a coffee!! click the link here https://www.buymeacoffee.com/RobinCle... For my 76mm and 102mm hinge jigs click here https://www.robc.co.uk My Amazon store https://www.amazon.co.uk/shop/robincl... Music by https://www.bensound.com