I made the bed = ‘wnes i’r gwely’ - but I don’t mean I took hammer and nails to it - I mean I put sheets/ duvet on it.
So would I say - ‘Wnes i roi dillad gwely ar y gwely’
Likewise: I stretched my legs - ‘Wnes i estyn fy nghoesau’ - not to make them longer but to take a break on a long journey.
Making a bed - I think most people would use “gwneud y gwely” or some form of “cymhennu’r gwely” / tacluso’r gwely", “cymoni’r gwely” etc (sorting the bed out rahter than “making it”.
Here in Ceredigion, we get around the making / doing uncertainty ni Welsh by using “gweithio” for the work of making. So “gweithio cawl” - making soup - and probably “gweithio gwely” - for making a bed with hammer nails and wood.
Stretching ones legs is a bit more problematic, as it’s an idiom. You don’t really stretch legs when you walk from the car to the coffe shop / toilet and back, and I don;t think I’ve ever heard a Welsh speaker using that particular idiom in Welsh. “Cymryd / Cael hoe bach” I would do, or “stopo am frêc” you would porbably hear from others