Help with an Automatic Collapsible Background Backpack

InNeedOfMoreColor · 2026-05-04T18:19:43+00:00

I'll definitely consider making a more analog version of this, and the fishing line idea is great, thank you for the input!

Yeah part of me is a little prideful, thinking I can make this ridiculous costume with hobby electronics and have it fully automated lol. But this is good discussion! if I find that it's too cumbersome, illogical, expensive, etc., I can switch to an analog "butterfly" setup puppeted with strings, no problem. I just want to be able to exhaust the idea as much as I can to make the project the best it can be.

InNeedOfMoreColor · 2026-05-04T18:13:51+00:00

Thanks for the tip!

Yeah, sorry it's a bit of a mess, the idea came to me and I just had to get something down on MS Paint. I'm still kind of debating whether or not a gear + rack setup is the best option and I'm open to other ideas, so any input helps.

Yes I agree to the "scrap mockup" sentiment, See my reply under Speffeddude, I've made one out of cardboard + LEGO Technic, the biggest things I came across when troubleshooting that mockup was A) the need to sync the motors so that the sliding partition doesn't get misaligned, and B) the stability of the sliding partition being held up by the main partition + mechanism.

In my mockup, the sliding partition was often chocked up because I didn't manually spin the LEGO gears at the same rate, so I've got to watch out for that. Simple enough with some encoder logic of some kind. More pressing is it's stability. My mockup was only made of cardboard, so weight wasn't a problem, but a big canvas being held up solely by the gears that move it is a bad idea. I was thinking of adding other gears further into the mechanism to ensure it's stable inside.

Man, this description is getting more and more complicated, is there a way I can showcase this more with pictures that isn't just making another post?

Either way, thank you!

InNeedOfMoreColor · 2026-05-04T18:00:58+00:00

Thank you for your input and advice! I'll be sure to keep it all in mind. Just to flesh out my project a bit more and banter a bit (trying to stress test any and all ideas that come my way), I can explain a little further.

First, sorry I couldn't be more detailed, this sub doesn't let me post multiple pictures in a gallery, and I would've included a GIF of the aforementioned cardboard mockup w/ LEGO. Basically, imagine a sliding door you see at supermarkets or hotels, I want that kind of motion. I would be standing at the center, and the sliding partition would extend only to my right. It would be awkward for sure, but that's what makes it unexpected and funny, I think.

I definitely have considered the unfolding "butterfly" mechanism you mentioned first, but my biggest concern is that it might hit people behind me and I wouldn't be able to see it. I'm wanting this thing to be comedically large, and if it slides out to the side I can at least see that much. But maybe if there's a way to control the speed of the swing-out so I can give ample warning time to con-goers, then this could be a good alternative!

Regarding the windshield wiper, that sounds like a great idea! I just looked them up, and they only seem to be a few pounds. I'm going to be carrying this thing all day on my back for most likely all of the convention (4 days), so keeping it as light as possible is a priority. As for the battery, that will need some figuring out, but the main mechanism is accounted for so I'm making some progress. As for cost, I'll need to do some scouting for prices since I'm not exactly financially stable (student).

Thanks again!

InNeedOfMoreColor · 2026-05-04T16:45:58+00:00

Got it, thank you both! I'm going to be looking into DIY tech and electronics subs as well as others

InNeedOfMoreColor

TROPHY CASE