You can find aluminium flat handlebars easily, as their construction is very simple. Even the stock ones from folding bikes are good enough. In this case, I chose the Litepro Monster flat handlebar which I used on the Dahon MuEX. There are lighter aluminium ones, but they flex too much for my liking, while lighter carbon ones are expensive.
Litepro Monster flat handlebar, 580mm wide. Cheap and good, with a clamp diameter of 25.4mm.
As for handlebar grips, lightweight lock on grips are available, but they are not that comfortable compared to Ergon grips. For weight weenies, foam grips are also available and they weigh very little.
For best comfort, Ergon grips are perfect. GP1 grips do not have bar ends, which is good as it means a lower weight and also does not affect the folding. I find that S sized grips are suitable for most people.
S sized GP1 grips
Large area to support the palm
Locks to the handlebar with a single clamp bolt to prevent rotation.
A pair of Ergon GP1 grips weigh 165 grams. Not for weight weenies, but its very comfortable. I use them on the Dahon MuEX and also the Brompton.
Finally, for practicality sake, a kickstand was added to the bike. Not essential but very useful!
Kickstand weighs 183 grams
Magnetix system to hold the folded frame together weighs 59 grams. Also not absolutely necessary but useful to have.
With that, I think I have listed down almost every single component of this new folding bike. Next, it is time to assemble everything into a bike!