If it is rainy, do not make toffee, wait a day after as the humidity in the air can interfere with the toffee turning out.
If cooking in a humid climate, consider running a dehumidifier in the kitchen while making your toffee
You can substitute other nuts or seeds for pumpkin, include them in the toffee itself, or leave them off completely if desired. Depending on the size, you may want to chop them.