Designing a custom-made casing that doesn't block the signal

I’m designing a custom casing for a sensor that sends its data with a SARA SSF r410M. How do I make sure that the shell does not block the GPS, LTE-M and NB-lo reach?

Suppose I made the casing out of steel or aluminium, would it block the signal? What are do’s and don’ts when designing such a casing so that the signals are not blocked? What materials to use?

As you probably understand, I don’t have much experience with electronics, but forward thanks anyway!