I made this 21st birthday mechanical card recently. I've seen this kind of card variously referred to as a cross fade card, a Venetian blind card, a changing picture card, and a disappearing picture card.
Whatever you call it, it uses a push and pull tab to change between two pictures.
A version of this card is in my go-to book for mechanical cards, Making Mechanical Cards by Sheila Sturrock. It is also included in Paper Engineering and Pop-Ups for Dummies by Rob Ives.
But this post is not about the card, it's about the printable neon effect that I made for the lettering and shapes.
How to make neon effect letters
There are a number of videos about creating neon-look signs, but they are mostly for Photoshop.
I wanted to use a vector program, so I created my neon letters using CorelDraw. Don't have CorelDraw? No problem! You can create neon letters with Inkscape (totally free!)
First, a relatively simple method of creating neon effect letters or neon line-based objects using CorelDraw.
I have created a "neon" Drop Shadow Preset for you. Download it and install in CorelDraw by dropping it in your Presets Drop Shadow folder. The path on my computer looks like this. AppData/Roaming/Corel/CorelDraw Graphics Suite X5/Draw/Presets/DropShadow
I can't speak for all versions of Corel and all computers.
If you prefer to use Inkscape to create neon letters or shapes, here's how to do it.