Well it can be done, but you should not do it, as this will defy bitcoins main purpose of existence i.e. freedom from centralised organisations. If you were to make a Visa card, you would basically hand over the control of bitcoins over a centralised organisation what good would that do to you, well it's true you can carry your card anywhere, but same is true in the case of bitcoins.

Also there were some people who have tried it, but they have spectacularly failed, and those who brought it were scammed too, think twice before you ever buy or consider this.