How many disc themes do you actually need?
The projector is sold on its own or bundled with four, six or ten disc themes, and that is the only real decision to make once you have picked a colour. It is worth thinking about, because the disc is what you are looking at — the projected scene is whichever one is fitted — so the bundle size decides how many different rooms you own rather than how many accessories.
What a disc theme actually is
It is the image. The projector provides the light and the optics; the disc provides the scene, and swapping it changes the ceiling completely. That is a more fundamental difference than it sounds — two discs are not two settings, they are two different objects on the ceiling.
Because they are interchangeable, the bundle you buy is not a permanent constraint on the hardware. It is a decision about how much variety you want from the start.
Projector only
This suits somebody who already owns compatible discs, or who wants the lowest-cost way to find out whether they like the effect in their particular room before committing further.
It is also the honest choice if you know you will use one scene and leave it. Plenty of people find a starfield they like in the first week and never change it, and there is nothing wrong with that.
Four disc themes
Four is the point at which the projector stops being one effect and starts being a thing you set. In practice most people end up with a favourite, a calm one, a dramatic one and one they rarely use — and that is a working set.
For a single adult bedroom or a living room this is usually enough. You are not going to change the scene daily, and four covers the moods a room actually has.
Six and ten disc themes
Six and ten make sense where the projector is shared or where changing the scene is part of the point — a child’s room where choosing tonight’s sky is the ritual, a room used by more than one person, or a space you decorate for occasions.
Ten is also the sensible gift choice, because you are choosing on behalf of somebody whose taste you cannot fully predict. The larger the set, the more likely something in it is exactly right for them.
Rotating rather than settling
If you do buy a larger set, it is worth deliberately rotating rather than defaulting. A scene you have looked at every night for three months stops registering; the same scene after a fortnight away is striking again.
A simple habit that works: change the disc whenever you change the bedding. It is often enough to keep it fresh and rare enough that you never have to think about it.
Where to keep them
Discs are optics and they pick up fingerprints, so they want a box rather than a drawer, handled by the rim. A small hard case near the projector makes changing them a ten-second job, which is the difference between a set you use and a set you own.
If the projector is in a child’s room, keeping the discs somewhere they can reach is what turns the bundle into the feature it is meant to be.