I’ve tried making 3D felt vessels before using 3D resists, like a rolled-up piece of bubble wrap and a balloon. Neither method was hugely successful – it was quite difficult to get the wool to hold together firmly enough around the resist while felting.
I realise that I’m beginning to sound a bit like a Nicola Brown groupie, but her book From Felt to Friendship really is a great source of inspiration. And it includes a technique for making a round felt pot using a flat circular resist. It worked beautifully – much easier and quicker than trying to felt around a 3D object.
The other useful technique was felting inside out. As you can see from the photo, I incorporated some wool slubs on the outside. Previously I’ve had problems getting these to felt in successfully, but by laying out the felt from the outside in, they were no trouble at all!
So I started by laying out the slubs on one half of the resist and covering them with dark blue merino. I turned the resist over and covered it with brown Icelandic wool. The middle layer on both sides was a dark wine-coloured merino, and the final layer (which would eventually be the inside of the pot) was white Icelandic wool. I rubbed and rolled, cut a small hole to remove the resist, turned it inside out and blew up a balloon inside the pot to keep it nice and round. The slubs had felted in beautifully, so I firmed up the outside by rubbing against a washboard until it was all even and smooth.
The disadvantage is that you can’t see the pattern on the inside layer while you’re working, so you need to remember which is the top and which is the bottom to avoid cutting the hole at the wrong end! I did this by adding a small tuft of blue wool to the top layer to indicate the bottom side.