I made a similar Teddy for a coworker I ordered the Bear off Amzon and then removed a bunch of that soft fluffy crap they use now and replaced with straw it was ok I did another one and used plastic bags and spray foam insulation but you have to be careful not to over fill so you cant sew back together.
A few years back I helped a neighbor clean out a storage unit and he had this 5ft tall straw filled teddy bear which makes the teddy bear very solid. As soon as I got it home I got a strapon and put it on the Teddy Bear and has been my bed buddy ever since.