I think to design robot shield with Picaxe 14M.
It has 14M CPU,L293D motor driver,Memory circuit 24LC32, programming input,male headers and some else parts.
Do you think it can be good?
look at this for some inspiration
I'm not familiar with the Picaxe microcontrollers, but I've built a similar shield using an ATTiny2313 microcontroller, two L298 motor drivers (the higher power versions of L293D) and additional circuits. It works perfectly.
I suggest you add some LEDs that can help you debug any problems that might occur. I've used five 3mm LEDs: 1 that blinks at each new package received from the master microcontroller and 4 that have the same output as the PWM signal that is fed to the L298 circuits. They are very helpful when something doesn't work as expected. The first LED allows me to see if the shield communicates with the master, while the other 4 leds show if the data received from the master is vaguely close to the correct values.