braid vs satin stripe

[Costi]

Can the side satin stripe of dinner suit trousers be made of the same “duchesse” silk (provided it is long enough) from which the lapel facings are cut? How is it best constructed an applied?
Or is it preferrable to use ready-made braid instead?
Looking forward to reading your valued advice.

[RWS]

Can the side satin stripe of dinner suit trousers be made of the same “duchesse” silk (provided it is long enough) from which the lapel facings are cut?

Yes.

How is it best constructed an applied?

I think it looks better running vertically, but I generally see it on ready-made dinner trousers and with the ribbing horizontal (that is, running the 1.5 or 2 cm. from side to side).

Or is it preferrable to use ready-made braid instead?

To my eye, far preferrable.

[Costi]

Thank you for your advice, RWS!

The silk I went for has no ribbing (it's duchesse, looking similar to satin but thicker, stiffer and less shiny). I was wondering whether it needed to be cut twice as wide, edges sewn into the trouser side seam and then folded flat and sewn with and invisible stitch to the trouser leg, or it could be simply cut 1 cm wider, the edges turned under and the stripe applied to the trousers...
Also, is it best applied symmetrically over the side seam (half to the left, half to the right) or rather towards the front while only 2-3 mms cover the trouser seam? Pockets are in-seam.