What Makes A Good Spandex Mermaid/Merman Tail?

[Mermaid Clara]

I have been thinking about making children's and maybe teen's mermaid/merman tails? i've have made 6 of them for myself through out the my mermaiding life.
But i was wondering what makes a good spandex tail? Good enough for parents to buy for their kids and buy again later? Is there anything that I would absolutely NEED to include for the tails?
I am going to offer two choices in monofins, the Finis Aquairus and the Finis Mermaid monofin. I will also offer an upgrade where i paint on scales and fluke rays, maybe even make it glittery or pearlescent. I will put in elastic and a lining too.

[mermaidopal]

There's so many spandex tail makers for children/ early teens out there that you should find a niche. I know fin fun has been popular because of their more realistic appearance, so I think offering to paint scales and fluke details is good.

[xaccer2]

Vrin

[xaccer2]

171.6

[xaccer2]

Perf

[xaccer2]

Perf

[xaccer2]

Иллю

[xaccer2]

Digi

[xaccer2]

Herm

[xaccer2]

напе

[xaccer2]

Wind

[xaccer2]

Alwa

[xaccer2]

Flow

[xaccer2]

Terr

[xaccer2]

Bist

[xaccer2]

Gran

[xaccer2]

Exch

[xaccer2]

Gala

[xaccer2]

Impr

[xaccer2]

Elai