I haven't seen the picks you mentioned in years but I suspect that three picks, a pair of scissors, and some supper glue and you could make a pick like you describe fairly quickly. This would give you the opportunity to experiment with sounds. As a silversmith I am perhaps more adventurous with this stuff because I have the components in front of me on a daily basis. So I will give it a try myself.

I make flat picks out of horn. They are heavier and less slippery and I like the way they sound.

I make my own finger picks out of sterling and the fit a little better than the Dunlop .025's I used for years.

I think it's more a vanity thing but they both do work well.

Don