"The Thumb" is a brand/model name for that particular manufacturer.
From what I have seen, around TBN, when the tractor-guys talk about "Thumbs" , they are usually talking about the device that does a similar function on their backhoe bucket.
For FELs (loader buckets) , the most used term is "
grapple".
If you search "
Grapple" on Google, you will find many manufacturers, makes and models.
If you search
Grapple on this forum, you will find a wealth of information from folks who have built their own, and know them inside-out.
Also, a note, while products like "The Thumb" appear to be priced within reach, you still must consider the price of the hydraulics that will be needed to make it function, which can be as much, or more than the
grapple itself. Just a little word to the wise, on that note.
On the other hand, a
Grapple is a handy-dandy device, and everyone that now has one will tell just how great it is to be able to grab logs, brush piles, barrels, rocks and chunks of concrete by simply operating a lever. it's a real labor saver and boosts productivity quite a bit, and has FUN Factor , as well.
Good Luck in your quest, hope this little bit helped.