Why alpaco.it exists
22 August 2026
I print a lot of small, boring, useful things: boxes for electronics, inserts for drawers, a hook for a specific spot on a specific wall. For years the routine was the same. Search for a model, find one that is almost right, download it, and then either scale it (which ruins the wall thickness and the screw holes) or open it in CAD and rebuild half of it.
At some point I wrote a generator for the thing I needed most often: a rugged box with a print-in-place hinge and snap latches. Type the inside dimensions, get a file that fits. It saved me an evening the first week, so I wrote the next one. That got a little out of hand. There are 34 generators now, and this site is where they live.
What it is
alpaco.it is a set of parametric generators that run in the browser. You pick a generator, type your dimensions, the preview updates as you type, and you download STL and 3MF files. That is the whole product.
A few rules I hold every generator to:
- It has to print. Every part comes out watertight, walls are 1.6 mm or thicker by default, and supports are avoided by design, not by hoping your slicer copes. If a combination of values cannot print, the generator says so in plain words and tells you which number to change.
- Your dimensions, not mine. A drawer insert is built for your drawer, an enclosure for your board, a stand for your phone with its case on. If you need a different size, you change a number, not a mesh.
- No account, no ads, nothing locked. There is no free tier and paid tier. Everything the generator can do, it does for everyone.
What it is not
It is not a CAD program. If you need a shape nobody has asked for before, Fusion, FreeCAD or OpenSCAD are the right tools. The generators cover the things people print again and again with small variations, and they try to do those very well.
It is also not finished. Some generators have been printed dozens of times, some only a few. Every page has a Report an issue button that sends me your exact settings along with the report, so when something comes out wrong I can reproduce it and fix the generator, not just your file. That feedback is worth more to me than anything else right now.
Why free
The site runs on a small server I pay for myself, and it stays free because I want it to be the thing I wished existed when I was scaling someone else's box for the third time. If it saves you an evening, there is a coffee button, and that covers the boring parts: electricity, the box that renders your model, the domain.
Where it is going
The list of generators grows from requests. The last few came straight from people describing a thing they kept rebuilding by hand. If you have one of those, tell me what it is and which dimensions matter to you.
This blog is for the longer notes: what a generator does under the hood, why a default is what it is, what I learned from the reports. Release by release changes live on the changelog.