To craft your own DIY mugs, you'll need to make a few stops for supplies before you get started. Take a trip to your local craft store to pick up paint pens in the colors of your choice. Oil-based paint pens work very well on mugs and glasses, hold the design and aren't messy to use.
These pens are typically priced between $2 and $4 each so look for craft store coupons that could save you around 50% or so off an item.
Note: While you can use permanent markers for DIY mugs, they don't tend to hold the design as long if your gift recipient actually wants to use the mug. Markers are fine to use if you only plan on displaying the mugs.
Your next stop is to a dollar store. Look for plain white ceramic mugs or clear glass steins or drinking glasses. The type of mug or glass doesn't matter. You simply want something that's blank so your kids will have an empty canvas.
Those are the only supplies you need. Just cover the area where your child will be painting and let her paint her own design on the mug or cup. The paint will dry fairly quickly.
When she's finished, place the mugs or glasses on a cookie sheet in a cold oven. Turn on the oven and set it to 325 degrees. Once the temperature reaches 325, set your timer for 15 minutes. Turn off the oven after 15 minutes but leave the mugs in the oven until they have cooled completely back to room temperature.
The design on your DIY mug or glass is now set. For extra protection of your mug or glass, hand wash after each use.