What joints should I use in my bear?
There are two basic types of joints: plastic and hardboard. Hardboard joints have traditionally been used since the early 1900’s. Plastic joints have been used in more recent times. In the past, plastic joints have been of poor quality and have not given a good, tight joint in a bear. In the past 10 years there has been a marked improvement in the quality of plastic joints and they can be used in almost any bear.
Hardboard joints are a pressed paper disc cut into sizes from 1/4” to 4” or more. They are secured in place by cotterkeys, tap bolts, nuts & bolts or hex bolts. Cotterkeys are inexpensive and easy to use if you have a cotterkey turning tool. Tap bolts are more complicated and need more tools to secure them in place. Nuts & bolts are another good option, but are not good for a head joint unless you leave a space in the head seam to joint through or glue the bolt in place. Hex bolts eliminate that problem by being held with an Allen key and tightened on the same side of the bear.
Generally, I would use hardboard joints in a mohair or collector bear and plastic joints in a synthetic bear or a bear intended for a child that may need to be washed.
If you are making bears for the collector market, use the market standard – hardboard joints, if you are making bears for your own and your family & friend’s enjoyment, use the joint you like best. Bears are supposed to be FUN and you won’t make bears if you are struggling with joints.
I would also point out that plastic joints in a real fur bear are not a good idea. They simply don’t work well in real fur bears. I would suggest a hardboard joint with a hex bolt.

What size of joints does a 12” bear take?
This really depends on the size of the bear’s limbs. A 21” bear with skinny limbs may take a 1” joint, as will a smaller bear with wider limbs.
A good general rule to figure out what size of joint is best for a bear is to measure across the bear’s hip or shoulder and take off 1/2” on each side. This takes off the 1/4” seam (on each side) and an additional 1/4” (on each side) so the bear will have a nice round limb.