They existed in WWI and i think you should only be able to build them in your capital..And you chould loan money from the NB (national bank)...And when you loan money you set on wath period of time from 1 day to 7 days or so and every hour you pay the money you borrowed divided by the days ranging from 1-7 + NB interest (gets bigger for the period of time from 5% to 15% or w/e)...And they should take directly from your money income per hour...And i guess if it takes from your money income you cant refuse paying because you need a capital tath 1 province minimum so you get a money income...Note: you can get a loan only from a bank that you can only build in you capital ! If you lose your capital you cannot get a loan...And i guess taking 3 days to build...And if you get a loan you lose some overall morale.And maybe if not National Bank it whould be Internation Bank at the marketing section and it wouldn't be in each country capital..Sorry for long post hope it will get implemented and people will like it !
Edit: And possible with resources too
Edit: And possible with resources too