Splitting solid markers is a great way to make crazy custom colors that you wouldn't be able to get anywhere. All you need is two or more solid markers and you're ready to go. You can even mix four colors!
Some of the most popular combinations are: Red & White, Yellow & Purple, Blue & Yellow, Orange & Green, Blue & White, Blue & Orange, Purple & Black, White & Black, Yellow & Red, Green & Yellow.
Start by unscrewing both solid markers to the top of the holder and take them completely out.
Take a razor and slice along the manufacturer line. It is easier to cut from both sides and have them meet in the center of the solid. Do this for both colors. Remove only one section of your newly sliced solid.
Match the appropriate, opposite sections together.
Screw the solid back into the holder.