Trying to identify a kid's show from the late 1970s, probably American, that featured puppets or marionettes with human hands. The puppets were kids who built some kind of space/time vehicle in their backyard that was kind of cone-shaped. They had creepy adventures with aliens and such. Again, the puppets' hands were human so they could do stuff on the show I suppose but the effect -- added to the weird sci-fi stuff -- was really creepy.
You might be looking for the "Outerscope" segment of an old PBS show called Vegetable Soup (1975–1978).
The segments featured puppet kids who launched a cone-shaped plank spaceship from their back yard. The following overall description is from Wikipedia:
Vegetable Soup is an American educational children's television program produced by the New York State Education Department that originally ran on PBS from September 22, 1975, to December 14, 1978. NBC concurrently broadcast the series on Sunday mornings, with at least some affiliates showing it along with NBC's regular Saturday morning cartoon lineup; this was a rare instance of a television program seen on both commercial and public television at the same time.
All 78 episodes of Vegetable Soup were digitized by the New York State Archives and made available online in the American Archive of Public Broadcasting. Episodes are made up of a mix of live action, cartoon, puppetry, and mixed-media segments.
The purpose of the program was to be a television series for children to help counter the negative, destructive effects of racial prejudice and racial isolation and to reinforce and dramatize the positive, life-enhancing value of human diversity in entertaining and affective presentations that children could understand and relate to. Vegetable Soup used an interdisciplinary approach to entertain and educate elementary age children in the value of human diversity.
The show combined music, animation, puppetry and live action film, on the subject of economic, racial and ethnic diversity.
Here is a clip from one of the "Outerscope" bits. The video quality starts out rough, but then clears up.
Might it be Jimmy Green and his Time Machine? It's marionettes and a time machine built by kids.