I took the inspiration and main design of @RAD3D's (Printables) great Dice Tray V2 and added the follow modifications:

• Shortened the height of the catch tray to make it easier to see the dice from sharper angles
• Added an inner lip to help make scooping the dice out easier
• Added a forward facing curled lip to make it even easier for 1 handed extraction
• Added a small retaining clip that should prevent the outside sleeve from slipping around when handling

I've tested a few designs and this one seemed to work great. I've been using it solidly with 4 dice for Can't Stop.