Evolution of suits over the years

[Torchwatch]

To make that suit work properly it would be necessary to stiffen the seams at the edges of the cut away section. A piece of Mechano at each end of the X would keep the upper and lower O rings separate and so keep the suit smooth.
If I were to redesign the suit's fittings I would have the O rings attached to the stiffening piece as one component, something looking like a flat horse bit.
Doing this would keep the suit fabric smooth and make the cross even more dramatic yet not be too difficult to sew in.

[Byron]

........and reminds me of my pet hate, the D ring.
How neat they look as new on the shelf in the shop as they link a carrying
strap (usually leather) to a woman's handbag or other apparel or equipment.
How ugly they then look after a bit of day-to-day use and have moved out of alignment.
PS: hope we're not talking metal meccano if other than dry posing is intended for that suit.

[Torchwatch]

Yes Byron Mechano did tend to rust once the paint was scratched, and no one would want rust stains on their swimwear.
The D rings you refer to would be cheap mild steel dipped in silver paint, as the paint scratches and chips they tend to look tatty. I would prefer stainless steel metal fitting, maybe not so bright at first but would retain their looks.
Real gold or silver fittings on your swimwear might look bling but could weigh you down.
Bronze or brass fittings might react with seawater and go green.

[Byron]

LOL - reminds me I once wore a "waterproof" wristwatch whilst sea swimming.
A bit of a misdescription if ever there was one and day by day thereafter the trapped
water under the face grew more and more algae so that I had a green timepiece with nothing visible any more.