In XCS, you will want to make rectangles, not lines. Make sure the default rectangle is unlocked and stretch it so it is long and thin.

Copy the line you made several times, rotate and place so they overlap to make an interesting pattern.

Select all the lines you have made, select ‘Unite’.

Create the Boundary shape you want. Common Coaster size is 3.5" to 4".

Place over the united lines you made previously.

Select everything and select ‘Unite at Overlap’. 

You now have your pattern. 

You will need to cut two different materials.

Wood (or whatever material your coaster is made of) and

Felt. For each coaster make one cut of each.

The felt will help the protect the table and provide a professional finish.

I decided to paint my wood to match another part of the gift using acrylic, but you may wish to use a clear coat. It you have beautiful wood you may even choose to just wax it. The point is to select something that will help create a barrier to water when used.

Once the coaster is dry, apply a thin goat of wood glue to the back side of the wood coaster. Only applying the glue to one side will allow you to align the felt more easily. Starting at one end, align the felt to the wood and pinch press it down. Once it is aligned the felt will ‘roll’ into place with your guidance. Burnish the felt down to make good contact and set aside to dry.

That's it! I'm sorry for the final image - I forgot to take a good picture before I gave it to her. They were given with a matching tray and some nice cheeses, fruits, and crackers. It was a hit!