Sketchup is one good, free option, but there are plenty of others. Tinkercad is a decent, free, online program. It’s attached to several custom order sites where you can get your 3D model actually printed!
Their tutorials and easy and provide yet another example of how fun & easy 3D modelling can be!
We’ll move on to the tougher stuff next week, but for now, work through the tutorials at Tinkercad and see what you think.