Machines which can't be constructed, but should be constructible (`*`)

[jennjwang]

Is your feature request related to a problem? Please describe.

There are machines which can't be constructed, only dragged. It makes little sense for them to not be constructable.

Describe the solution you'd like

List of things from discussion:

1. treadmill
2. punching bag
3. ergometer
4. water purifier

Additional context

Please add things which you think should be constructable but are not!