If you've ever retired a seasonal design and had customers ask when it's coming back, or discontinued something and later wondered whether it's worth relaunching, a simple waitlist solves two problems at once — it captures genuine interest as real data rather than a vague guess, and it builds a bit of anticipation that can turn into a stronger launch than a cold relaunch would.
The simplest version doesn't require dedicated waitlist software — a Google Form linked from your shop announcement or a specific product's "currently unavailable" state, collecting just an email address and which specific design someone's interested in, is genuinely enough for a small shop. This ties directly into the email list building covered elsewhere; a waitlist is really just a specifically-motivated segment of that same list.
Announcing a waitlist opening (rather than silently retiring a design with no clear path back) also signals something useful about your shop's process — customers see that popular items get relaunched based on real demand rather than just disappearing arbitrarily, which builds a bit of trust and reason to actually engage rather than assuming anything retired is gone permanently and not worth asking about.
When you do relaunch, emailing the waitlist specifically, ahead of any general announcement, gives your most clearly interested customers first access — this can meaningfully help a relaunch's early sales velocity, which as covered elsewhere directly helps with initial search ranking momentum for a re-listed or newly listed item.
A realistic threshold worth using before actually committing to a relaunch: if a waitlist genuinely accumulates a meaningful number of interested signups over a reasonable window (even a modest number, relative to your shop's typical scale), that's real, concrete evidence worth acting on — versus a waitlist that barely gets any signups at all, which is useful information too, just pointing the other direction, suggesting the retired design may not be worth the relaunch effort after all.