What is the bead made of?

You could use a piece of cord dipped in epoxy and taped in place.

I bend an 1/8" thick strip of ash with a heat gun to the shape of the hatch opening,
round the edge and cut off a piece about an 1/8" high. Two pieces, each half of the shape, joined
on the deck centerline. Tiny and kind of tricky.

I now bend an 1/8" x 1/2" strip of ash and add it to the edge of the deck lip
the way Paul does. This larger piece is easier to handle.

It's important to use a wood with good bending properties like ash, to make the tight
bends without frustration.

Rob