Hello! I've got a clever technique to help you make a map for your gaming and story telling needs. The map making process is simple and it will be a fun project your can share with friends and family.

Supplies

You need to have different sets of dice for this project. You will need a new set for each feature that you want to display in your map.
You can use a poster board made from cardboard or one from cardstock. You can get these from any major retailer or any arts and craft store.
You will need some paint and paint brushes that have a flat edge to them. The colors you will need are brown, gray, dark blue, light blue, green, gold (optional).
A pen and pencil

Step 1: Assign the Dice Pool Some Attributes

For my project I wanted to display 6 different types of features on my map, and each feature had it's own symbol. To replicate what I did you will need to gather quite a bit of dice. As an example of what I mean I will share with you the dice pool that I assembled for this project. For my dice pool I had my X-Wing miniatures dice (cities, icon =dot), Heroclix dice (mountains, icon=caret), 20 sided dice (forests, icon=tree), small 6 sided dice (points of interest, icon=square), larger sized 6 sided dice (lakes, icon=oval with bumps and ridges with wave symbols in it), and my Star Wars role playing game dice (river, two parallel lines). Each pool is easily distinguishable from the other, and you should aim to do the same when you are assembling them. You can have any amount of dice in each pool, but you want to make sure you have enough to get a good spread on the map when you roll everything in the next step. Don't forget to write down or take a picture of what each dice pool represents.

Step 2: Ready! Set! Roll!

There is a couple of things you need to do before you can roll the dice.

Clear and prepare a clean working space for your map. I chose to go with one of those large posters that are made out of cardstock as seen in the images that I had shared here.
Lay out some newspapers or towels underneath the edges or your soon to be map. This is useful for when you are ready to paint.
Find a large enough container to hold all of the dice.
Once you have all of that ready you will need to give the dice a good shake or two to mix everything up.
ROLL THE DICE! Be careful not to loose any stray dice under your furniture.
That was fun right? By now it should look a little messy, but that's okay. Now that the dice are out you will need to go and draw in each icon with your pencil.
You can choose to draw in one type of feature at a time or what I did was work my way right to left, bottom to top, and all the features at the same time except for the river. I wanted to save that for last as I wanted to see how I can add twists and turns in the body of the river.
If you get tired or get cross eyed you should take a break.
After I drew in the features I took a moment to look at how I wanted to draw the river. I got luck as most of the dice happened to have fallen near each other in a nice cluster. Where ever there was a large cluster I decided to draw them in as a large lake instead of individual rivers.
My forest were looking a little barren. It was something I expected as that was my smallest dice pool, but hey you can just blame the dice right? Okay, bad lame joke aside its time to move onto the next phase of this project!

Step 3: Give the Map Some Color

If you were lucky like me there was some space where the dice didn't fall onto.
For me I had a lot of room to create a title, a legend, and an ocean.
I saved that part for after the painting was done.
You can choose to paint your map in any order you want, but for this project I started with my water features.
A tip before you paint. I tried a technique called dry brushing. There are a lot of videos on the Internet on how to do this, but I will go on and describe this technique for you here. To dry brush you need to get some paint on your paint brush and wipe it off on a towel until there is barely any paint coming off of the brush. Now take your brush, and take nice and light brushes on your map until there is a noticeable amount of paint on the map. What this will do is the paint will hopefully only catch onto all the bumps and ridges that paper has in it. I did this because I wanted to experiment, and see how grainy the cardstock was because its a common crafting material that I use in my terrain projects for my table top games. I never painted directly on this stuff before.
Now dry brush the light blue for your lakes and rivers. Its okay if you go over the lines or you make it too dark. There's nothing wrong with a little blip here and there. I've got shaky hands, and I think the map came out okay.
After the lakes and rivers are done I went ahead and dry brushed the dark blue color for the ocean that I drew in on the left side of the map.
You are making good progress so far. Take a break if you need to. The next feature that I painted was the forest. I dry brushed some green onto where the forest icons where. I painted a circular shape over them. No need to be neat on this. It's okay if it's too small or large.
I repeated the same process except I did this for the mountains.
Since all of the features have been painted in you can now start on dry brushing the land brown. I have a tendency to paint with a heavy hand, but do try your best to keep a light handle when painting.
The very last thing I painted on was the background color for the legend. I wanted to give the map some extra flare. No dry brushing here. Layer the gold paint on like there's no tomorrow.

Step 4: Inking the Map

You are nearly there my friend. I promise this will be over soon! In this phase of the project you will need to come up with a name for your map. What does the map represent? Is it a map of a country or maybe its a map of a forgotten corner of the world? Its up to you, but for this project I chose it to be a chunk of land that used to be a colony. Making maps like this can help a writer get a visual on how things might look in their story. You will need to use a pen here on out. Be sure to do your best in centering the text and to not make the title box so large! Oh all that empty space...
After the title is done you need to find a suitable spot to drawn in your legend and North arrow. Don't forget to pen your name after you drew in all of the symbology
Go over each feature in the map with your pen. This will give them a nice bold look.
You will need to name some of your features. For this project I named the big lakes, river, ocean, mountain range, cities, and points of interest.
CONGRATULATIONS! You made a map!! I hope you had a fun time with this project. You can make just about any kind of map with this technique. Thank you for following along and have a nice day!