Create rectangle with 1mm stand-off from object

I will be creating 3-dimensional letters and would like, at the same time, to surround each one with a rectangle 1 mm larger than than the letter. The rectangles would be lightly burned onto 3/4" wood and used as a guide to cut, on my saw, blocks to glue the letters onto. In Lightburn each letter would be centered in the rectangle. I don’t want to create the rectangles manually as there are many letters and precision is necessary. Another way of doing this is to note the height and width of each letter and input those dimensions, plus 2 mm, in the rectangle tool, then use the bullseye tool to center the letter in the rectangle. But…is there a faster way of doing this?

I should explain that I am a letterpress printer and will be making wood type to fill in gaps in my existing fonts and to create copies of complete 19th-century fonts. All blocks will be exactly the same height; only the widths will differ, with an “I” much narrower than a “W”, for example. The sequence will be:

1. Turn off rectangles. Cut letters out of 1/8” board.
2. Turn on rectangles. Lightly engrave image of each letter and its associated border onto ¾” board. Use the border lines to cut board into blocks on my saw. Use letter image to place letter precisely into position on the blocks.