that would be simple. they are just a ramp where you control when to let them loose. from there, you'd make each target a switch when you knocked them down, and a solenoid to set them back up, then just make a box to go around it and a comp to remember how much each target is worth and to display your score when your done. as for making one, i'd buy one if it were me, too much cost for so little, and you could probably pick one up for a 100 if you found one. try talking to your local arcade owner for some coin-op names to contact.
good luck.