Is there a good reference on how to construct these out there? When I tried searching the forum I didn't see anything.

I can't say for sure but I suspect there might be valuable discussions in on of the many secret "Hey, 50 posts, you're a regular" forum sections...

That being said, there are quite a few related forum posts from years past around and, if you don't have any luck with the Magic Cafés search function, you might try Google with search terms something like "shim card site:themagiccafe.com"

Good luck

I have been gaffing my own for a few years and there is not a lot of reference out there for how to make shimmed cards. I figured it out more by taking a shimmed card apart and taking notes on what went where. A lot of “gaffers” play it close to the vest which is cool because they do it as part of their magic business. There are very limited talk of card splitting (or peeling) in older books (Expert Card Technique I believe). The best tutorial book I found was https://www.lybrary.com/the-gaff-factory......750.html and https://www.lybrary.com/magicians-diy-ti......831.html

There are some good splitting videos by Blake Vogt https://blake-vogt.myshopify.com/collect......lume-1-2
And various blogs, articles, videos by others... It is just something you need a strong base for then you move on from there.

Making simple gaffs are fairly easy and inexpensive once you can split cards well but it can get very pricey if you decide to buy specialized tools.

Often it is better to buy a specialized gaff than to get everything involved in making one. Especially if you just need one or a few gaffs.

Any good source for tricks using them? I ended up with one in a gaff set (I was after something else in it, so it was a bonus). I've used it once so far because someone gave us "Kissing Boston Terriers" Salt and Pepper shakers that we don't use, but happen to have magnets in their noses. Fun to have one "sniff out" the spectator's card. Would love to see what else people do with them.