I have changed the Otto body a bit as can be seen on the attached picture. Nothing special.

I did that with the relatively new, for schools and hobbyists free-to-use, "CAD in the cloud" program Onshape, a SaaS application. In that respect it is comparable to Tinkercad. Only it has professional features (just like the already known Fusion 360) and Onshape is not yet found here via Seach.

Therefore, here is a recommendation, including for use in STEM education, especially for modeling Otto variants. With Onshape, this is possible in with teams without the need for expensive equipment. Numerous Onshape educational videos can be found on the internet, including this recent one [https://onshape.wistia.com/medias/j3j3t1hhpp]. Especially after minute 40:00 is interesting.

A free Dutch Onshape course is available for Dutch readers [https://drive.google.com/file/d/1pDidrwy6VAeUFayQO85PIsunbHo8cqnI/view?usp=sharing].

If you like, give it a try.