add some painting or oil to make the box weatherproof

add more switches e.g. for lights

add frontlights etc

add an internal light that shines through the spare holes in the rocket (there is a spare terminal block and a reserved space on the pcb)

install a simple miniature voltmeter in the box to monitor the batteries

you may want add a little schotky diode after the fuse to prevent wrong polarity. Especially when you switch to external power it is essential to protect the circuit in some way.

use nicd or pb rechargeable batteries instead of alkaline batteries

use 12V instead of 6V

add sockets for charging (you may add a switch to switch from charge to operation mode or ensure you do not power on and use the box during charging process)

add sockets for external power like more powerful pb or car batteries etc

add a socket and connect an external switch that must be hold down during operation. the switch should be connected between start button and the pcb

you may want to remove the buzzer or add a switch between buzzer and pcb optionally disable the buzzer to limit the test current to a minimum of ~2mA (then only the red ultralow current start led is used to limit test current to a minimum of ~2mA)

there are 12 spare holes in the panel to add leds, switches, buttons and sockets etc

a lot of spare sockets, holes and soldering points are on the pcb to extend the features and use of the startbox

e.g. you can add a switch and button to arm and fire smoke, flashlight bulbs before the rocket launches :) or trigger a countdown module … etc etc etc