In our climate I wear tops like this all year round, just adding various weight jackets on cooler days.
When sewing clothes I usually don't use a pattern, even for complex items, instead I cut and sew using existing garments as a guide, designing and custom fitting in the process (trying it on after each stage to check). After completing this top I decided to make a pattern from it for easier duplication. I am quite happy with a no fuss, easy wear design like this which requires no zip or buttons. I have plans to make another one or two when the fabrics come on sale.
Sew-in medium weight interfacing works well to trace a pattern onto. I wrote my directions directly onto the pattern pieces and also stitching lines to clarify. Some time ago I bought 4 metres of this interfacing when it was on special, with the intention of pattern making, and had it rolled onto an empty fabric cardboard tube at the shop for crease-free storage. The interfacing is sturdier than paper, withstanding pinning better and could always be repurposed.