Settlers of Catan and other board games based on tiles often fly apart. I made an acrylic cover to settle the tiles and keep the other pieces in place.

Step 1: Mapping Out the Space

Assemble the game the way it would be when you use it to figure out the way it best fits on the acrylic sheet. For the same reason that motivated me to build this, I found it helpful to tape the outside edge down: otherwise the pieces move around.

The piece of acrylic I bought was just smaller than what I really wanted, but it does the trick.

Step 2: Mark the Intersections

Mark the intersections of all the pieces. To remember which pieces are done I flipped them over. This step and the following ones are a bit tedious - there are 72 edges and 19 pieces.

Step 3: Lay Out the Troughs for the Roads

In Settlers of Catan roads are placed on the edges between tiles. Since the tiles never seem to lie flat, the roads are never quite stable. I cut troughs into the acrylic to keep the roads in place.

Lessons learned working the acrylic
I am using a router with a 1/4 inch bit. I initially ran it at full speed but the acrylic melts easily and was just gumming up. I had an speed adjuster around that you can put between the plug and the outlet. There was a lot less gumming up with a slower speed.
The cuts were cleanest if I started in the center and rolled the router along the fence to the edges, taking off another layer with each sweep until I had the full depth (about half the thickness of the acrylic). I eased out of the trough in the middle as well since stopping at the ends left that part all uneven.

Step 4: Cutting the Holes for the Number Tiles

Settlers of Catan uses number tiles placed on the main tiles to indicate which roll of the die will generate resources from that tile. These number tiles also tend to wander off.

I drilled holes just bigger than the number tiles through the acrylic to keep them in place.
For just the game of settlers there really should have been one number tile hole per main tile, but I am hoping to add some tactile markings in the second hole (hopefully an Instructable to follow). and these markings would be accessed through the second hole.

I used a Forstner Bit to drill the holes, but a spade bit might do the trick.

Lessons learned working the acrylic
I drilled about half the holes on a drill press. Even with very little pressure the acrylic often cracked from the point outward. Also, the paper got stuck on the blades a lot, making me stop the drill to clean it off.
I was not able to reach the holes in the center in the press so I used a hand drill. That actually worked a lot better. By tilting the drill about 5 Deg and moving it around the hole that way the outside of the hole got scored without the whole point having to go in, and that stopped the crack from going past that circumference.

Step 5: Adding the Edges

I used some of the scraps from cutting the acrylic to a hexagon as edges to keep things in the right place under the acrylic.

I cut the material into strips on a table saw (using a skill saw on it just shattered the edge, and it was one of the noisiest cuts I have ever made). I sanded the sides that would connect and used super glue (cyanoacrylate) to put it together. I should probably have used more but I didn't have more around.
It turns out the sanded acrylic gets translucent again where there actually is super glue.

Step 6: Testing 123

Here is the result. I found getting it onto the tiles easiest by assembling the game from one corner and sliding the acrylic over as that corner was in place.

I am planning to do a second part to make the game tactile to be able to play it with a friend who is blind... hopefully I'll get to another Instructable about that.