For something like that what's gonna be best is to do one-offs using this thread as your guide:

https://pinside.com/pinball/forum/topic/my-guide-to-making-your-own-reproduction-plastics

Having them printed only makes sense in more bulk kind of numbers, it's too expensive to make just a couple practical. And you couldn't sell them here if you used "some pics from the internet" if you made a bunch, Robin would shut down the thread for copyright infringement for using other people's pics.

I've thought about doing my own, but with original art so they'd be safe.

People have done some nice repro ones though, no reason you couldn't apply that same technique to your own, can use any image you want for private use, and show pics of it etc.

If you want them to look nice you'll need some high rez images. A slingshot plastic is roughly 4.5" x 1.5", depending on the game. So to print at 300 dpi you'd want an image at around 500x1400 pixels.

Not that hard to do.

Use 1/16 acrylic and laser cut or jigsaw the plastic slings or whatever you need. Then use a water slide decal, I would use a white for a semi transparent and clear for full transparency. Use the correct paper for the correct printer, laser or inkjet. If you want the printed image to look perfect I suggest vectoring the image in Photoshop or Inkscape. This removes all artifacts and color differences from scan light when the clear/semi plastic reflects during the scanning process. Clear coat the image before placing it in water. Print the image mirrored so it sits on the underside of the plastic when applied. Let dry then clear a few more coats.

I've made quite a few plastics for myself using water slide decals. It's a lot of work, but sometimes there just isn't another option. I will offer one tidbit that I learned along the way. Using a program like Photoshop once you get the colors right and printed, I often go back and reprint over the same decal with all color removed and only the black remaining. Getting a good dense black seems to be the most challenging when doing these and the second print of black only seems to help a lot.

Any drawback to using plastic protectors instead of cutting your own? I know they're a little bit larger, but if it annoyed you, you could make your images larger to match. Would save a lot of time, and the need to go out and buy tools.

I find creating the plastics themselves far easier than making the decals. We have a store called TAP Plastics that has a scrap bin loaded with plastics. I prefer to make mine out of 1/8" Polycarbonate (Lexan)....pretty much indestructible. I rough cut the shape with a RotoZip than sand to shape with a bench top belt sander and a Dremel.

It seems in my experience the depth of the plastic is somewhere between 1/8 and I/16th. I have used both but perfer the 1/16. The image has less to pass through with the smaller thickness. It might be a little trickier (flexing) to cut if you don't own a laser cutter. I also make clear acrylic circular washers that stick out a little to protect the plastic. Shouldn't be an issue though but I have leftover plastics with each of these cutouts.

Just reviving this thread in case anyone is taking on the DIY plastics challenge since times have changed...

I found a great source for lasercut, polished edge plastic to be made for you, low cost, no minimums, in any shape you need. They can work from sending in the originals, or from a drawing by email. I think he uses plastic in-between 1/16 and 1/18 that measures roughly .093" thick plastic. It's very nice stuff. And with the new water-slide papers so inexpensive to buy on Amazon these days, I think this whole process to make your own plastic has become pretty easy.
Contact David at www.upkickpinball.com and [email protected]