I've always started runner beans early, about 4 to a pot, but my
relations all plant them straight into the ground.

For sweet peas my father-in- law used to cut strips from plastic
fertilizer bags and roll and staple them into tubes. Probably about
the same size as a loo roll centre. One tug split them and brought
the roots out without damage for planting. Best sweet pea seedlings
I've ever seen.
I had a particular sunny spot to grow them, visible from the kitchen
sink, that I always used. To keep the soil sweet I used to
completely wheel barrow out the soil every spring and replace it with
fresh, over the top of a layer of compost.

Prior to retiring he also used the plastic coffee cups from the works
vending machine. He had made a tool from a cone with a sharpened piece
of hacksaw blade on the end which, when rotated, was just the right
size for cutting the bottoms out.

Bill
Derby