Hanji Doori is a shop and it also has a great online web page(in Korean) where you can order all of their supplies. The shop displays a large range of Hanji craft supplies and on this trip to Seoul I found it tucked away on the 3rd floor of a building in Insadong. You can buy, papers, cutouts, molds, hardware, kits with paper, kits without paper, brushes, glues and electrical fittings for lamps.
As is often the case, these shops are discovered by word of mouth amongst the expat community and I became aware of its location through the networking I was able to do at the presentation 'Hanji - After Korea' in Seoul, last week.
It was great to walk into the shop and find a lovely lady, Catherine, who spoke very good English because she had spent some time in New Zealand, and she was able to answer all my questions about Hanji.
If you get a chance to go to Insadong it's well worth a visit. Check out the Hanji Doori website. I'll certainly go back.