I propose a thread to share simple, cheap and clever little get-arounds for everyday problems encountered.
A super simple handbrake can be acheived by using a hair-bungie (elastic hair tie)
If you have bar-end caps, trap a hair-tie with it then pull the brake on & hook the tie over the lever.
Strida sell a bar end with an elastic already fitted for this purpose.
On my GoBike I find this very useful as it stops the the front wheel from moving, which stops the forks from twisting, which causes the bike to fall over (usually when you are trying to strap something on (the bike! ) or when you lock it to a post.