Commercial reed diffusers are very fancy and nice but with several drawbacks:1) they are pretty expensive
2) the scent emitted can be a way too strong and "fake"
3) You never really know what's in there!!!
A simple way to prepare your own scent diffuser is to use paper tissues and few drops of natural essential oils. You can put the tissues in a small container, in the bathroom bin etc.
If you have several essential oils you can either go for a bouquet of scents or you can use different oils for different part of the house. HAVE FUN!