DIY Line Laser pointer

Hi all! Apologies if this has been posted already but some quick searches on this subreddit didn’t yield any results for this topic. I’ve seen several posts with people looking for line laser pointers. Obviously if you hold a normal laser pointer really close to the surface at an angle, you kind of get a line, but it’s not terribly useful and lacks all of the snazz of having a working line laser generator/projector.

I purchased “The Army Painter” marker light for $5 under the (mistaken) assumption that it would project a line. It’s about half the size of a pen, powered by stacked coin batteries and has an unscrewable head. I was bummed that I purchased the wrong product and wanted to see if I could salvage the situation since I don’t have much use for a normal laser pointer.

After some googling, I came across this page where the author talks about converting a similar pen laser to a line by using a Fresnel lens. I’m not certain where you would purchase fresnel plastic at a retailer, but I noticed that the pattern on the Fresnel plastic was very smilar to the top resealing portion of the near infinite number of plastic baggies that come with the X-wing expansions. A dash of ingenuity and a heaping serving of laziness yielded this: working line laser from my $5 laser pen! Imgur

It’s not perfect. I would assume if I had the correct type of plastic in there the Fresnel optic would more evenly distribute the light from the laser instead of generating a weaker line with a bright center as pictured, but for me, this was more than sufficient for the task of generating a line. One other quirk I encountered was that the baggie material may not lay flat- if the material bends, the line it outputs will curve slightly, which defeats the purpose of using it to measure the straight lines for firing arcs.