Diy Coat 2

The lining is first cut, exactly the same size and shape as the top material, then you can carefully cut 1/4 inch more off around the edge.

When you have both cut, place them on top of each other. 
Fold over the Tartan material to cover 1/4 inch of the lining, then stitch in place.

The belt is made the same way. You can use Velcro strips for fasteners, they are much easier to fix the belt together than other methods. 
Fix a strip of Velcro to the top on the right, and the underside left.
 

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DIY Coat 3