Most people posting here have enough unused credit card "headroom" to get them through a month; so the main thing for an emergency fund is that you can get the cash out of it with low or no cost within that month.
Some use bond funds to do it, some use bond or CD "ladders" - buy a bond expiring in 12 months that is 1/12 your emergency fund each month, and in a year you'll have a rolling "self built fund" that you can get 1/12 of every month with no penalties.
Bogleheads forum has tons of discussion around these kinds of things.
Most people posting here have enough unused credit card "headroom" to get them through a month; so the main thing for an emergency fund is that you can get the cash out of it with low or no cost within that month.
Some use bond funds to do it, some use bond or CD "ladders" - buy a bond expiring in 12 months that is 1/12 your emergency fund each month, and in a year you'll have a rolling "self built fund" that you can get 1/12 of every month with no penalties.
Bogleheads forum has tons of discussion around these kinds of things.