Guest post by Dalibor
First thing to do was to make a frame. Then add layers of fiberglass. Filling the voids and irregularities with git and then the painting.
Cutting a side opening and making a lid 
Laying of fiberglass fibres 
Covering irregularities with git, before sanding and painting
I opted for the black colour:
Housing holds all the batteries, wires, connections and a display that shows battery state, consumption and other parameters. It also has a contact lock with three switches and a jack for battery charging. Switches are used to turn on the display, speed limit and cruise control.
Photo gallery of the finished project of Polar Viper electric bicycle modification.