A forummer bought a 16 inch rims from me and has find difficulty in sourcing the 20/20 holed hubs for the rims. It's not available in Malaysia actually but it can be bought online from Taobao, China. I have no idea with regards to the said forummer's front fork width as there are 2 different widths. One as used by Dahons and Terns are 74mm and the other the usual 100mm (usually those with disc brakes). The 74mm offers more rigidity and stronger as the spokes are not too angled from the rims. That's why Dahons and Terns choose that width, probably.
There's another option , though. You can get the front hubs (20 holes) from here if you are using 74mm.
http://bicyclebuysell.com/item/311012/kene...bearing-freeposand if you are using 100mm forks, you can get the adapters here.
http://bicyclebuysell.com/item/333141/lite...pter-dahon-ternAs for the rear, you can go for either a 24 hole or a 32 hole ones and skip a few holes while lacing. The distance is so small, I don't think it will affect the truing of the rims and more so because the rims are only 16 inch diameter. So, use with confidence. The only drawback is.................most LBS are not interested to do it as there might be a few spokes modifications. You might need to adjust the length of the spokes.
I would suggest though that you take this set. It is the 24 for the rear and the 20 for the front. This eliminates a lot of problems.
http://bicyclebuysell.com/item/204486/nova...24-free-pos-w-mAnd if you want to use the regular , more easier and off course cheaper as it is common 32 holes for the front and rear, I have drawn the spokes lacing patterns. The red dots on the smaller circle are the SKIPPED holes. Both the 24 and 32 holes are fine if you look at the lacing of the spokes. Shouldn't be a problem. Good luck !
This is the 24 holes lacing.
and.............this is the 32 holes lacing.
If you have contacted me earlier, I could have done it for you but I am now in Taiping, so it's a bit hard. If you want to mod the spokes yourself like I do, get this ; The size of the spoke nipples are a bit special though. Most nut and bolts store stocks only 2,3,4,5,6mm etc but not 2.5mm which is the size for the spokes. I got it from Central Nuts and Bolts in Jalan San Peng, K.Lumpur. You get longer spokes, for mountain bikes, these are the easiest to get anyway and then measure and cut to length needed and tread it.