Along the top of the bonnet theres a metal channel which the bottom edge of the bonnet doors slots into (the bonnet sides hinge upwards) to hold them in place when opened. I represented this on the models with a strip of .030" x .010" plastic with a slot cut down its length with an Olfa type cutter. A pic;

Thanks to Ruston for info on this.

Axleboxes were carved from 3 x 1.5mm plastic strip. On the OOn3 loco they could be fitted straight on but on the EM loco they had to be thinned due to the lack of clearence between the frame sides and the wheels. I found it easier to make the boxes for the EM loco from the same material as the n.g. loco and file them down rather than use thinner plastic. Another pic;

Also seen attached inside the frames are the axlebox adjusters, represented by the red plastic rod, which are used to move the axleboxes backwards and forwards to tension the drive chains.

The axlebox detail is quite crude but in my defense they are mostly hidden by the axlebox gaurds and when finished will be painted dirty black.