I assembled my bits, neatly trimmed my fabric and interlining and ironed it all:
I added a long zip to go round the three sides so that I could easily replace the contents if necessary.
Then I trotted off to the supermarket for 2kg of rice (which was not enough and I used about 3.5kg in total!!) Oops, forgot to add that I made another bag with slightly smaller dimensions from scrap blue fabric to hold the rice and lavender inside.
And here it is all done, the main box is upside down and the zip is at the top instead of the bottom, but when all is said and done it does the job and holds the door open, so I suppose I could call that a mini success...
When this was finished I was suprised at how big it is, but once it's in front of the door, it looks just right.