use the side attachment points...
start with something like a t connector
attach 2 20cm plastic extenders either side with the top attachment point.
attach 2 20cm plastic extenders either side with the bottom attachment point.
and so on so on, until you have the length you want
then attach spikes to all of the side attachment points that if ^^ was done correctly will all be facing forwards. if you spikes are red rotate them a little and then you can attach them
