For the visual learners out there, here's a tutorial on creating a 3 x 3 grid with a lined acrylic block.
This tutorial will show you how to line up a shape that isn't a circle or square. Circles and squares are actually much easier because all of your aligning can happen using the intersections of horizontal and veritcal lines on the block. This butterfly is a rectangle (wider than it is high), so we'll have to do a bit of tweaking to get the spacing right.
1. Place your image in the exact center of the block, both horizontally and vertically. This block has a small circle marked in the center to help locate it. Ink the image, and stamp the central image of the grid. Notice how the vertical lines just inside the right and left edges of the paper are parallel to the edges and have roughly the same amount of blue paper extending beyond. That's how you can center without a ruler.
2. Ink the image again, and stamp below the first image. Notice the grid line that goes through the center of the butterfly stamp aligns with the first image I stamped. The bottom of the wings are lined up on the horizontal line just above the stamp. Remember that.
3. Now stamp above the central butterfly, this time aligning the centers of the butterflies with the central vertical line and the top of the first stamped butterfly with the horizontal line below the stamp.
4. Now move to the right column. Here's where it gets a little tricky because the alignment won't be the same horizontally as it was vertically since we're dealing with a shape wider than it is high. If we lined the grid up with the far left edge of the wings of the central column, the right column would end up too close and the whole grid would look off balance.
Look for a point on the central stamped image that you can align with a vertical line on the block. In this case, I took the left edge of the tail of the wing as my alignment point. See how the three stamped butterflies all rest on that second vertical line to the left of the actual stamp? Just make sure the horizontal line at the center of the butterfly also aligns with the center of the already-stamped butterfly as well.
5. Now repeat above and below, using the vertical and horizontal lines to guide your stamping.
6. Do the same thing to the left column of butterflies.
7. And so on.
8. And now you have a grid that looks fairly balanced! It's funny how the photo shows the left column slightly closer to the center column than is the right column. In real life, that minor difference doesn't show at all. Weird.
9. I like to line up sentiments on the center line of the acrylic block as well.
10. Stamp the sentiment on the edge of a piece of scrap paper to test it. Some sentiments use fonts that fool your eye into thinking they are straight on the block when they are not. Notice how the white line below the sentiment is completely parallel to the edge of the paper.
11. This is mostly straight...good enough for handmade, at least.
13. Line it up on the paper and stamp as you did the very first butterfly on the grid. Check out the vertical lines just inside the edges of the paper. Again, I am a little off (although it looks perfectly fine in real life).
14. No matter. The end result is fabulous.
I hope this helps! You should also know that I messed up the first attempt and had to start over. These things happen.
It's only paper, and we are not machines!!!!
P.S. What if you have a wood-mounted stamp and want to create a grid? That works best when you use a ruler and put pencil dots on the paper where each image should go, and then use a stamp positioner to place the images precisely. This is time-consuming and persnickity, and I wouldn't even try it with an image that wasn't a circle or a square so the spacing is completely even.