You guys are great for doing this. I would ask that you provide a tutorial on how you do this, as I am keen to make some flags for periods I am interesting in and for which I doubt other suppliers will ever do. Hope you guys can help with a nice 'How-to' tutorial. 
OK download a picture from here
https://www.google.co.uk/search?tbm=isch&hl=en&source=hp&biw=1053&bih=890&q=curtains&gbv=2&oq=curtains&aq=f&aqi=g10&aql=&gs_sm=12&gs_upl=1626l4035l0l5930l8l8l0l2l2l0l99l525l6l6l0&gs_l=img.12..0l10.1626l4035l0l5930l8l8l0l2l2l0l99l525l6l6l0.frgbld.#hl=en&safe=off&gbv=2&tbm=isch&q=theatre+curtains&revid=2058958004&sa=X&ei=g7dlT__tI8Oq0QXpueyuCA&ved=0CEEQ1QIoBA&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=8d3f7fddeae8bc27&biw=1053&bih=890 ...all curtains, don't have to be curtains could be a sheet ... anyway this can be pulled wide creating folds...then you turn it into a black/white photo...you can create tons of grey folds in flags and pick the ones you want and bang them in a folder.
OK next .. got to keep it simple because it can go right over ones head here and you can get losted with what i am saying...lets download a flag off google
like this, could be anyone you want, i created this myself with stars bars ect because i wanted no comes backs to say i stole other peoples work.

ok this was a sheet i pulled wide, i suppose you coukld take a photo of you're own bedsheet if you wanted to...never thought of that till now.

Now the idea is to put these two together, you open both in Elements 7 in boxes called layers, then you scroll down to a button called multipy,.
creates this

All sounds very simple but its not because its a matter of finding other buttons placing these pics in the layers and numbers for size ect...believe me i kicked the dog lots of times with frustration trying to figure out how to create stuff and spents hours on hours getting my head around it..now i even found a faster way of getting it done...really good advice is get these two software and i have no problem helping you create what you want...cus you are gonna need me...
gonna take a picture now of my bed sheet