A Needoh is a soft, stretchy fidget toy, and people collect them. There are fifteen series, from Groovy Glob to Dig It Pig, and collectors keep track of which ones they own, in which colour, at which size, and whether the toy has been retired. Then they try to log it.
Most collection apps open with the same form. It asks for a name, a description, maybe a price, maybe a photo. That is five fields, give or take, chosen by whoever wrote the app on the day they sat down to write it.
A Needoh needs eight fields: product name, series, colour, size (the same toy comes in standard, mini and jumbo), release year, whether it is retired, retail price, and condition. Condition is the interesting one, because for a Needoh the options are mint in box, like new, good, squished and well loved.
A squished Needoh is still a Needoh, and it is still in the collection. Condition is a fixed list decided before you sign up, so squished is not on it. You pick the nearest wrong value, or the detail goes into a notes field.
Two more collections with nowhere to live
US state quarters. One coin for each state, released in the order the states ratified the Constitution or joined the Union, five a year from 1999 to 2008. The Mint estimates 147 million Americans collected them. A collector working through the set does not need a title and a description. They need the state, the year, the mint mark (P for Philadelphia, D for Denver, S for San Francisco), the denomination and the mintage, because a Denver strike and a San Francisco strike of the same design are not the same coin. In a generic app, those five fields go into a description box.
Mechanical keyboards. Twelve fields: brand, model, layout (75%, 60%, TKL, 65%, full-size, split), switch type (linear, tactile, clicky, Hall Effect, Topre), the exact switches fitted, keycap profile (Cherry, OEM, OSA), keycap material (PBT or ABS), connection, mount style (gasket, tray, top, sandwich), release year, price and rating.
Try reducing that to name, description and price. Any keyboard collector who has tried already made the same decision you are about to. They opened a spreadsheet and kept going.
Where the problem comes from
App makers have nothing against coin collectors or fidget toys. The problem is that a schema is a decision, and most apps make it before the collector arrives.
Choose the fields up front, and you have chosen what any collection on the platform can be. Items become rows in your table. Anything that does not fit the columns gets squashed into a notes field, or dropped. The collector fills in what the form allows and stops thinking about the rest.
That shape is fine for the collections that happen to match it. Books match it. Films match it. It is why so many catalogue apps look interchangeable, because at the data level they are.
Hold a Hall Effect keyboard, a squished fidget toy and a San Francisco quarter at the same time, and the model shows its edges. What those three share is a shape that only the person doing the collecting can name.
The other way round
Collectd hands the decision to the collector. A new collection starts as an empty form, and you build the fields yourself from ten types: text, textbox, number, dropdown, yes or no, date, price, rating, year and measurement. The only rule is that exactly one text field has to be the primary title, because that is the value shown on item cards, list rows and gallery headers.
A Needoh collection ends up with eight fields, one of which is a yes/no switch called Retired. A mechanical keyboard collection ends up with twelve. A state quarter collection ends up with five. Those three lists are real, each field in them can be added today, and we did not design any of them. They came out of the field types, not out of a template library.
Templates are useful and there is a place for them, but a template is somebody else's schema with your collection poured into it. An empty form asks the question no app asks: what do you track?
What changes when you answer it
Ask a keyboard collector to write down their fields, and you find out which part of the hobby they care about. One writes down mount style first. Another writes down switch weight, and stops there. A coin collector who adds mintage is telling you they care about scarcity. One who adds mint mark is telling you they buy strikes.
None of that requires a longer field list or a bigger form. The collection ends up describing the collector's own version of the hobby instead of the version the app shipped with.
If you want the mechanics, the field guide walks through the ten types and when to use each one, and building your first collection takes about five minutes.