Start by determining what style/ era of furniture you want to make. There is a demand for practically any high quality furniture in 1/3, 1/4, 1/6 or 1/12th scale made out of wood. I would stay away from the foam board, it would be much harder to create something sellable out of foam board, no matter how hard you try it will never measure up to the real deal. Decide your skill level, how good are your woodworking skills, how much (money, timber, time) are you willing to invest in practising and improving your skill. Be honest with your self and start with furniture that falls inside your comfort zone. Look at a lot of examples, either on the net or in books. Make patterns by scaling up or down miniature or real patterns.
It's ironic I came across this thread because earlier today I found a free tutorial for making a doll table. It was originally made for American Girl dolls but I'm sure it would be just as suitable for MSD/SD sized dolls. Here's the link. http://dolldiaries.com/doll-play-day-80-the-easiest-doll-table-ever/ That same site has a bunch of other tutorials for making American Girl sized doll furniture that you can sift through under the "Doll Furniture" tag. http://dolldiaries.com/category/doll-furniture/
Hmm, you know I usually think furniture as a kind of high end accessory. But going off Kimpossible's search suggestion (looking at American girl stuff) lead me to a picnic table tutorial. Given how many people like out door photos and group shots of their dolls, even something as simple as that might be a good product.
You know, If your dolls are under 18", I recommend going to stores like Home Goods, marshalls and ross. these kind of stores often have AG sized props like beds, couches and some of the pet beds they sell, are perfectly scaled for BJD's. I just bought a bed for my 16" leona at Home Goods for only 19.99! I couldn't believe it. I grabbed it right away. I started making my own bed for my doll, but finding this one was a life saver because they now have a place to sit and hangout. file://localhost/Users/susanacohen/Pictures/iPhoto%20Library/Originals/2012/Sep%2011,%202012/Photo%20on%202012-09-11%20at%2009.40.jpg
Thanks for the tip about Home Goods. We just got one in my area. I'll be sure to check them out. As for designing furniture, it's very similar to designing anything else. Getting your ideas out of your head and organized is a good first step. If you're designing from scratch, and not just bodging cereal boxes together, I would suggest drafting each view of the piece to scale. More details make better plans which means less wasted time and materials. I don't know about other folks, but I have a real problem with a storage space shortage. I'd be interested in attractive and creative furnishings that slotted together but could be disassembled for flat storage. As for the qualities of foam core versus wood products, well, consider where and how it will be used. Foam core isn't pretty, so you'll probably want to cover it. It's easy to cut, and you don't have to worry about grain, so there's less waste. Most glues or tapes stick to it. Staples or tacks go in easily, but they might come out just as easily. It's fairly strong and inexpensive compared to the same square footage of wood. Wood is harder to work with and requires more finishing, but it looks luxurious.
http://ana-white.com has free plans for doll furniture. several beds are on there and at least one bench/table set. search under toys. her human sized plans look easy to scale down as well.
2079realms.com A Wholesale market min. 10 max 100 of BJD accessories. They have some iron furnigutre for diffrent sizes. I personally have an AOD MSD and I use different 18 inch doll Target/Wal-mart/American Girl furniture for them. Also search at flea markets, garage sales, or craft stores like Michaels/Hobby Lobby.
I use a lot of American Girl furniture, I like for all my dolls to have beds. Also, etsy has a lot of amazing furniture, in varying prices.
Although this thread is very old I thought I would add that searching for 'apprentice piece' (which are minature but perfectly made versions of larger furniture made by apprentices to stop wood being wasted) or 'salesman sample' on ebay can bring up some great small scale wood furniture, although they can be pricey a bargain can be found!
Etsy is a good place to get furniture in the right size from artists. They look really detailed and realistic. It can get expensive just like clothing & accessories for the dolls, but someone mentioned hobby lobby, craft stores have different sizes of furniture that can be customized with fabric and such yourself for less expense
I saw a lot of tutorials on youtube where people used the box that the doll came in for the base of a bed. Then they added a headboard made out of foamboard, bedding, a dust ruffle etc. I thought it was a cool idea because it would obviously fit the doll and it also offers a place to store your original box. If you didn't want to glue things directly to the box you could create a framework around it with foam board. I think one of the tutorials actually did that? Several people cut a headboard out of foam board, added a layer of batting, then covered it with fabric and tufted it. It looks nice if you are going for that sort of look. I've started saving a lot of boxes from different things and at some point I want to start fitting them together and seeing what they turn into. I also bought one of those plastic coated shelves that you use in cabinets for a base for either a bed or a couch, I haven't decided yet. You could store things underneath it. There is also a tutorial on Pinterest where a person took a tupperware type bin, made a separate dust ruffle and quilt and used that for a bed. Then they stored their doll clothes in the bin. If you wanted to use that idea you could stick a headboard to the wall and slide it up against it. I bought a triple shoe rack on Amazon that I am going to make into a bunk bed. I will leave out the middle shelf. My doll is MSD but it's big for him, so maybe it would fit an SD size doll? I bought foam cushions from Hobby Lobby, pillowcases for bottom sheets from Dollar Tree, and some microfiber dish towels that match also from dollar tree for bedding. I THINK it will look nice once it is finished but I haven't started working on it yet.
I can not figure out what size of furniture l should use with a 1/5 bjd. It's driving me nuts lol. I have 18" doll props (food) but not alot of furniture.
I saw that lomi's playground on youtube used an IKEA changing table as a SD sized canopy bed. It occurs to me that you could also make it into a set of bunk beds...