Yupo Jelly – it sucks!(and that’s good)

Yupo Jelly is a transparent PET sheet with micro-suction cups on the back that stick to flat surfaces. Since it works using suction, it doesn’t leave any adhesive residue when removed.

It is typically used for putting up signage temporarily. It does not support printing via inkjet or laser printers however and needs one of the following techniques: UV offset, UV silkscreen and UV digital. It is fully recyclable.


A ruler is dangling on the side, being stuck to the yupo jelly paper.

Material ConneXion Link

Manufacturer Link : The manufacturer is easy to get in touch with and eager to work with artists. Samples are provided freely. Product is available for purchase from the manufacturer easily. Swatches available through application here. Distributors.

Product Datasheet1 / Product Datasheet2

Interesting use cases:

  • Laptop webcam cover
  • Put it all around your house: mount your phone on the walls
  • Holding down mylar or similar light material while laser-cutting
  • Holding PCBs for SMD assembly

Custom fit silicone glove(with embedded electronics)


3D scanning:

I scanned my hand using iPad structure sensor. The sensor had a lot of trouble scanning my hand separate from my body, so I set up a board with a hole to scan my hand as an object instead. Many thanks to Ridwan for helping me with the scan.


3D modeling:

A 3D model produced was processed and reduced in meshmixer. The resulting model is uploaded to sketchfab here. I want to try out wrapX for redefining the mesh.

I then made a shell around the model and split it in two. I had to be careful to split it such the two halves could fit on the model when 3d printed. The separation between the model and the shell is 2.5 mm(1/8″) this is so that I can use 2.5mm(1/8″) acrylic pieces as spacers to ensure the model is centered inside the shell then closed.

3D Printing:

I printed the models using Cura and Ultimaker 2+. Since the model is relatively smooth, the layer height does not need to be fine. Even a 4mm layer height with 6mm nozzle is good. There were a LOT of failed prints.


Take care of the orientation of the build. It can have a huge effect on the time taken for the print.


The print needs to be cleaned up before use. I sanded the prints with a Dremel, going slow to prevent melting. Then I covered the entire surface with epoxy. The epoxy adheres to the rough surface well and allows the silicone to be removed easily.


Adding electronics:

I stuck discs of 2.5mm(1/8″) acrylic on the model, spaced regularly and test fitted the shell. Then I stuck neopixels and a flex sensor on the model. I used silicone wires to connect the sensors so that it sticks to the poured silicone easily.


I followed standard techniques to cast silicone using a vacuum chamber. I’d recommend this video for instructions.

What went wrong:

The silicone I used(EcoFlex-30) has a relatively low working time of ~20 minutes. So there wasn’t enough time to degas the silicone when pouring it into the thin cavity between the model and the shell. The bubbles got trapped in the silicone and ended up in the final solid cast. Also, the silicone is not very durable and tears easily. And the electronics are not flexible enough to allow the cast to be removed from the model without damage.


What I would do differently:

  • Model in a different way so that the casting is in a perpendicular direction. Having a shorter distance for the bubbles to travel will allow for easier casting.
  • Design the mold with air escape holes at the bottom
  • I would use silicone with longer working time.
  • Use shorter stretches of electronics separated by coiled silicone wire.

Bio-inspiration in soft robotics

Fig wasps and figs trees live in a mutualism ecosystem where the fig tree provides nourishment to wasp eggs and the wasps pollinate fig flowers. This is a mutually beneficial arrangement. The lifecycle of a fig wasp is illustrated below.

Life cycle of a fig wasp

So, female wasps pollinate the fig flowers by entering the fig with their pollen laden body. Parasitic wasps have co-evolved to get nourishment from the fig trees without pollinating the flowers. They do this by drilling into the fig from the outside with their long ovipositor.

From an engineering perspective, the ovipositor is a flexible, maneuverable hollow tube with sensing elements at the end. This mechanism has been studied by multiple researchers with recent findings experimentally studying the mechanisms of insertion. The tip of the ovipositor is enriched with zinc, presumably for hardening.

A parasitic wasp drilling into a fig. Photo credits: Lakshminath Kundanati.

This problem can have interesting direct applications in any number of in vivo experiments e.g. in neuroscience for non-destructive probing of brain cells.

Novel experiments in cable mechanisms

Cable mechanisms consist of a tension(/compression) bearing cable running through a compression(/tension) bearing channel. This mechanism can be used to transmit force over relatively long distances with light and flexible material. Notable examples include Bowden type 3D printer extruders, bicycle brakes, early car throttles etc.

While experimenting with sphincter type channels, I discovered that to get symmetric contraction of the mechanism it is important to apply force through both ends of the cable as shown below.


I used this mechanism to make Cookie Monster, an evil cookie jar that doesn’t let you take cookies. If you reach in and grab a cookie, it mouth of the jar traps your hand and won’t let go until you drop the cookie back in the jar.


I want to make a robust version of it, keep a delicious cookie or amazing toy inside and exhibit it in a children’s museum. I can just imagine kids trying all sorts of ways to get at the toy and failing. Ahhh.. it’ll be fun to watch that! If you’re someone who can make this happen, I want to get in touch with you!

I also experimented with developing a lightweight upper body exoskeleton to help me do pull-ups. But I gave up on the idea when I realized that a robust mechanism would require at least some metal machining. If you want to develop the concept further, feel free to reach out. I’d be happy to share thoughts and experience.