side for Halloween Evil Eyes from toilet paper roll core

thingiverse

These are sides for toilet paper roll-based evil eyes props. This is inspired by many projects that one can find with [a simple search](https://www.google.com/search?q=toilet+roll+halloween+eyes), such as [this one](https://www.organizedchaosonline.com/2013/10/02/cut-eyes-in-toilet-paper-rolls-for-halloween/) or [this one](https://www.duckbrand.com/craft-decor/how-to-cardboard-glow-eyes) or [this one](https://web.archive.org/web/20201224131439/https://cdn.homesthetics.net/wp-content/uploads/2017/09/5486eb9f515150b53a8f01c5200eab58.jpg). Essentially, one takes the cardboard rest of a toilet paper roll, cuts nice eyes into it (painting it on the outside is optional), and then illuminates them from inside. For that purpose a 3V lithium CR2032 plus (red) LED works great. And typically even "spent" lithium cells still work just fine for this purpose, even when used for a whole evening or night. An additional current-limiting resistor for the LED is not needed, the internal resistance of the lithium cell is typically enough. I usually print [a little holder/clip](https://www.thingiverse.com/thing:4907153) (design by [arcaneoctopuslab](https://www.thingiverse.com/arcaneoctopuslab)) for the LED that connects it to the CR2032 (which works great!), and also put some baking paper from the inside over the cut-out eyes to diffuse the light a bit. The problem with plain cardboard rolls is (a) that the light also comes out at the sides and (b) that they are difficult to position because they tend to roll away on even the slightest incline. Initially I made hexagonal sides also from cardboard, but due to the usually wet weather around Halloween these easily soak up water from the wet ground and then essentially dissolve. So I created these sides, which ensure that the prop no longer rolls away, which keeps the light inside, and which allows you to position the eyes just as desired. Print two per toilet roll, very little infill like 5% is enough as they do not need to support any weight or structure. You likely need to adjust the diameter to your specific toilet roll, so in addition to some example diameters I also include the OpenSCAD model that you can easily customize.