How to make a snap-on lid to a box?

I am creating a case for my Raspberry Pi Zero. It has two pieces, the base and the lid.

I’d like the lid to close securely and then stay in place, and am trying to figure out the simplest mechanism that can lock it in place. Perhaps a snap-fit mechanism? Can anyone provide guidance on how to add something like that?

Often that’s done with small raised tabs on one part and shallow grooves on the other.

And then once the lid is locked in, how would I open it?

Big hammer? :smiley:

You could make a little recess on the outside to allow a coin or a small flat screwdriver to be inserted to pry the lid off.

Thanks for the suggestion. I’d like to try the idea of making 4 tabs in the lid and little grooves in the base of the case. I’m unsure of a few things, like how to size the tabs relative to the grooves so they fit snugly. Are the tabs supposed to be the same size as the grooves, or a bit bigger (how much)?

I’m also trying to understand the proper way to design this (I’m a Sketchup beginner).

I suppose I should create the tab shape for the lid first, and then copy it, potentially resize it (?) and explode it onto the case base with negative extrusion to create the associated grooves?

How do I create a groove like the one here in black?

case_lid_attempt_3.skp (309.0 KB)
case_base_attempt_3.skp (799.7 KB)

Here’s my latest attempt at creating a snap-on closing mechanism for my box.

Though I haven’t tried 3d printing it yet, I’m wondering if I did something wrong… when I went to convert to GCode, Slic3r told me there were 5009 errors with my lid, and the preview of the model looks crazy in Slic3r…

This is what things look like at the moment:

I just tried printing this and the lid came out shaped like a triangle instead of a rectangle. Any idea why?

This is my lid file case_lid_attempt_3.skp (309.0 KB)


Looking at the green image you have posted, there are parts of the model that the grid lines do not appear on.
This seems to be the same part that is missing on your print.
I don’t know a lot about 3d print but I have noticed this.

czar1na. I assume you are using this to “Learn” about 3d printing. Other wise I would go out and buy a box and save some $. You can then also install and cut foam for inside to protect you item…
Or make the box a component , check the entity info, if it does not report a vol. then it is not solid.
I would recommend you start over, making the various items components (there are only a few major ones) and then you can assemble at the end and print .
Componets isolate geo. for you so you can “build in place”, go to window, model info, components and you can set various options for visibility which should help.
Install the plugin in solid inspector and it will help you ID problem areas.

Was this a solid as reported by SU, my guess is not, check entity info if it does not report a vol. it is not solid;
The slicer has a number of settings especially important for the lid =>#1 will be in fill. There are most likely help files at their(slic3r) site and on net.
The lid needs to be fixed now, once it is solid another print test is necessary. Wasting time and material if not.
I’ll try more fixes later


Simply re-posting your models with a few changes will not make them ‘solids’.
Your base, as posted in several threads previously, has almost 100 errors which need fixing before it’ll be a solid.
Your somewhat simpler lid has almost twice as many errors !

You seem to be somewhat oblivious of the basic requirements needed to create a manifold solid.
Despite many posts advising you on good practice…
This is perhaps evident when you still post your hopeful SKP files including guide-lines and dimensions, and without the geometry which you hope to be 3Dprinted not grouped [or in a component-instance].
If it’s not in a group etc then how do you know if it’s a solid ?
If you used Entity Info it would tell you if it were.

By taking your half-baked geometry to be 3d-printed it is all but likely to fail !
Wasting your time and your money !!

Please reread the various threads you have spawned.
They all offer sound advice on how to achieve what you want.

Ignoring good advice, and continuing down a flawed path is unlikely to ever give you what you want !

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czar1na, I won’t even attempt to compete with the competence of my fellow contributors’ design abilities, however, from my experience in SketcUp and 3D printing, may I suggest the following.
Design the joining geometry first (no matter what your final project’s choice is). Make both the male and female several mm thick (usually just the perimeter of each)… just enough for the connection to take place without distortion or breakage. Play with that till you get the right fit thereby saving a helluva lot of filament and extensive print times. Then when you nail the joint, design the box around that. You may find that your result will influence your upcoming box design. If you design the box first and then play with the coupling you may find that you will be changing designs more often than my missus nags me about changing my sox.

As in this example of a holder for a coffee carafe,

The small printed “rim” was my 4th. attempt before I was satisfied enough to fully design (with the contours) and print the final product. It progressed from a square that was about .5mm too tight. to a square that fit snug, to a 1/4" radius corner and finally a 1/2" corner. Mybe a few vinos less and I may have nailed it the first time.:yum:

PS. I am assuming you have ready access to a 3D printer and you don’t have to contract out.

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