Making Giant Raspberries With Optimized Design for 3d Printing

As a designer you often come up with crazy ideas, but sometimes It's the client that comes in asking for something a bit out of the ordinary. This is one of those cases.

The company in question was holding an event to advertise the launch of a new product, a raspberry-chocolate frozen treat, and wanted to decorate the space with giant raspberries. The bigger the better.

The idea was to have them hang from the ceilings, and to also have lamps inside of some. And of course he whole thing had to be accomplished in less than 10 days, so the venue could be decorarted in time for the event.

I first searched for models online, but the ones I found were not really optimized for 3D printing, so they were too material and print-time heavy when scaled up. Due to the time constraints this was a deal-breaker, so I had to go back to the drawing board and come up with a solution.

In this instructable i am gonna show you how I made the design for the HUGE raspberry decorations so they would both look amazing and print quickly using as little material as posible.

If you want to make your own giant raspberries or raspberry lamp shades you are gonna need:

1. Access to a 3D printer.
2. Red filament for the berry
3. Green filament in matching shade for the stem.

The first thing I did was to try to get a feel for the geometry. I am not good at sculpting so I wanted it to be leaning on the geometric side without it becoming a bunch of spheres clumped together.

I decided on three rings of beads clustered together. Each ring would be composed of repeated instances of an ellipsoid made by revolving an ellipse, as shown in the picture. The key thing was making all the operations whilst leaving everything loosely defined. This meant that I could then play around with the shape and disposition of the beads to narrow in on the berry look.

This allowed me to explore how to get the most realistic distribution without having to oversee too many variables. I found that the best results came from repeating the beads with quite an overlap, both with adjacent beads on the ring and with the other rings. This left no holes in between the beads and made the berry look like more of a whole than a mere cluster.

Also, to better acomplish the integration, the middle ring beads were placed slightly rotated so the beads would form a staggered pattern and better fill the gaps.The alternated placement also looks more natural than a simple tiered version would.

Furthermore, by doing the model in such a straight-forward yet easy to edit way I was able to show the resulting cluster to the client as an early proof of concept. This assured me that they approved of the overall look, before I moved on to the more technical details that are required to get the model ready for printing

The next thing to decide had to do with printability. Ideally you would want a flat base for it to print reliably, but if the base extended outwards too much it would eliminate the divisions between nodules at the base and thus look way less natural.

I decided to go for a middle point. A small base would add stability and serve as a place to mount the stem, and the base of the nodules would be printed with very localized supports.

Once the shape of the overall solid was decided it was time to ootimize the inside for printing. Usually you would rely on infill for the internal structure and call it a day, but in this case size and reduced printing times were a must, so the best solution was to turn that solid into a fine tuned shell. That allows to eliminate infill entirely and rely purely on perimeters for printing!

That approach has a catch though: to fully take advantage of the shell design you must scale the shape to its final size before doing the operation, or you may with too thick a shell later on.

So first I scaled each variant to its final size and then proceeded to hollow out the shape.

Now infill is not in there for show. Without infill you need to ensure that all top surfaces are fully supported. So once the model was hollowed out I added a custom made structure that supports the tip of the berry.

I took into consideration that the slicer later on would use 0% infill and crafted it in such a way as to only rely on perimeters whilst keeping shell thickness uniform in critical areas.

The elimination of infill and custom support structures went a long way towards reducing material and printing time enough for us to manage to fabricate all parts in time for the venue. And who does not like shorter print times!

Next came the design of the stem.In this case it was intended to serve two purposes, Remember when we said the berry would rely on some supports at the base nodules? Well it's a given that those supports tend to leave a mark on the final print so the whole design of the stem revolved around solving the hanging and instalation and at the same ime disguise and cver the marks left by the supports.

Moreover, they rely on a technique I've picked up along the years, where the finished part is reheated after printed with hot water and mold it into its final shape. This allows fr the design to be faily straightforward, bur gain lots of flourish and organic feeling after the post-processing with hot water.

The model itself is pretty simple, the shape of the leaf hets repeated around the base of the stem, then a little knub with a perforation gets added. The only key detail are the ridges. located on the edge of the leaves, they stabilize the shape during forming when using the hot water method for post processing. They provide additional structure with minimal increases to print time.

.Once the Raspberry strain has been crafted i's time to grow them!

Here are the STL files for the berries in case you want to make your own!

The model is designed to pint with no infill and only calls out for suports in the bottom part of the nodules,

PETg is recommended for temperature range of operation but they print grea on PLA too.

Just plant your little GCODE in your printer of choice and watch it grow in a couple of hours!

Once you have a nice harvest of freshly printed berries you can add the stem to them. Although the stem design may seem kinda flat and boring this is completely intentional. The idea is to use heat to mold those flat points into curves for a more realistic natural flow.

If printed with the curved appearance from scratch they would be extremely fragile and difficult to print. This way they print faster, are more resistant and the leaves can be given slightly different curvatures each time for extra variance.

The process is fairly simple. Start with a bowl filled with some tepid water and then progressively add boiling water. Once you notice the heat is enough to soften de leaves you can submerge them and shape each by hand to your liking. With PLA the material starts softening at around 60 degrees Celsius, so using boiling or neat boiling water is not necessary at all. Keep it as cold as possible for extra safety and style those stems away!

Once moulded you can stick them to the berry with cianoacrylate, they also have holes to add a peg if needed for added strength.

And Voilà! you have your very own homegrown giant berries.

As for the event with my client it was a huge success!

There were giant raspberries hanging from the ceiling everywhere, and some had lamps installed inside of them for added effect.

Alongside the berries there were also enourmous pink clouds and a fucsia lighting that gave the whole place an eerie otherwordly appeareance.

Definitely made an impression, and nobody could figure out how they had managed to get their hands on giant raspberries!

Thanks for reading this instructable, help yourself to some berries!