Given the resilience required of the folding bikes, alu is not providing much of weight advantage while bringing risk of failure somewhere down the line. Gust looks like a nice bike, but I could not find a single photo of it being equipped with fenders. Is there any problem with having fenders on that bike, if you know?
I don't know if there's any particular issue with that but if it's helpful, mudguard isn't really the norm here in Indonesia and Singapore for custom bike. Probably because most are casual riders.