This is what I made last year for little one when he was only 7 months old at Christmas and he just sat on top of it like a little Christmas pudding!
The mat evolved as I worked on it as I didn't really have a set plan of exactly what I wanted to make. I knew I wanted a range of touchy-feely fabrics and bits of ribbon and to try to make different themes/scenes, so the outcome turned out to be flower shape with each scene looking a bit like a petal.
I used bits of fabric that I had lying around, the only thing I bought was a larger piece to back it and some squeakers for inside the sun and the bus. I'm not sure why a sun might squeak but it's been lots of fun anyway!
The leaves have different patterns and textures and some have crinkly paper inside to make a nice scrunchy sound.
The space scene has a moon with craters which are stitched on top of wadding to give a padded look. The stars are the shiny lame again and the rocket is made from felt. It can fly around the moon but it's attached with a ribbon and can be secured on the moon with a piece of Velcro.
I tried to use lots of colours, prints, textures and sounds to make the mat interesting for a baby, but didn't buy anything specifically for the mat, I just tried to use what I had (apart from the squeakers).
He has enjoyed using it and hopefully will continue to do so as he grows and develops, learning to use it in different ways.
I thought carefully about safety while making this as I know my little one put absolutely everything in his mouth at that stage. It really goes without saying that if you want to make one, choose materials which you think are safe and suitable for your baby. Remember to ensure everything is securely attached to the mat and never leave your baby unsupervised when on the mat.