Walt,
Now that it's been described, it sounds very similar to a product called "Glue Dots". They are small gobs of glue stuck to a smooth carrier sheet. You press the dot to an object and it adheres. Then you can place another object on the dot and adhere the two pieces to each other.
Useful for placing figures temporarily on the layout, although the dot is a little hard to remove later from some surfaces.
There is a similar system on a larger scale called a "Zyron" machine. It is a roller device that transfers adhesive onto a material, so that it can be glued onto something else.
It is big among the scrapbookers who are always gluing diecut pieces of cardstock, photos, etc. to an album page.
The machine can also be used to laminate business cards, etc. with a protective plastic sheet.
What I'm not sure of is whether the glue used is classified as "permanent" or "peelable". Most times permanent is preferred for scratchbuilding.
Not to get too long-winded here, but there is another similar product that is very permanent. It is a two-sided adhesive material that is used to hold ceramic tile in place on vertical surfaces until the thinset mortar sets.
Like the glue dots, you transfer the adhesive to a surface. Then peel the protective carrier and place the tile on it. It is great for holding rock castings in place until you can grout around them.
I have also used it to attach building flats to a Masonite backdrop, to attach small tiles to MDF in constructing retaining walls, etc. A package goes a long way since you will only use small portions of sheet at one time.
It is found next to the ceramic tiles at HD or Lowes. 
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Jim