by Erik Es - Amsterdam, July 3, 2018  
  There are several ways to create 3D prints that have one or more
loose parts locked inside of them. One easy way is what I call
"insertion printing". This can be done by printing a hollow object.
During printing the top will still be open so it is pretty easy to drop
something inside it.
That's how I made this "Marble Cage", for instance:
You can pause the printer at some point to insert an object, but that will
almost certainly cause a visible seam in the print, especially if it has
very thin walls. So it is much better to insert something without pausing
the printer (although that is more tricky, especially with small prints).

Timing is essential. If you insert the object too early, the print head
starts hitting the object that was placed inside, ruining the print.
If you get distracted, by the time you look at the printer again, the top
might suddenly be closing up - too late...
After a few of those events I realised that a timer is very useful.

One of my favourite designs incorporating insertion printing is one I
made in 2013: a SHIP-IN-A-BOTTLE.

Some people have strange hobbys. For centuries there have been
oddballs that kept themselves busy by putting ships into bottles.
I have always found their work quite fascinating.
A ship in a bottle is a visual conundrum - it seems impossible to get
that ship into that bottle. Many people assume that it is done by
forming/shaping the bottle around the ship using some kind of
glassblowers trick. Not so. SPOILER ALERT: If you don't want to know
how it is done, skip the next bit.

The model ship is (mostly) constructed outside the bottle. To get it
into the bottle, it is made in such a way that the masts can be raised
by pulling on some cleverly placed strings.
The ship, masts down, is inserted through the opening of the bottle
(which is usually relatively wide). The strings are then pulled to
deploy masts and sails. Hey presto !
With special instruments the strings are glued or knotted to the model. Then the loose ends are cut to hide the evidence of how it's done. Sometimes extra ornaments (like cannons and such) are added to the ship, and often some kind of sea is added to the scene as well, using plaster or wax or such. This all requires special tools, which these shipbuilders mostly make themselves. Wonderful people.

So I decided to create a 3D printed ship-in-a-bottle.

First I designed a bottle. I gave the bottle one flat side so it can be
placed on its side without rolling around.
For those who are wondering: yes, the bottle is designed as a solid
shape. Turning it into a hollow bottle is done by adjusting the
appropriate settings in the software that controls the printer.

Then I made the ship. I decided that it would be nice to use a fairly
modern design instead of an old-fashioned sailship.
I also realised that it would need to be a rather bold design, as any
small detail would not be visible through the printed bottle.

So I modeled the ship like this:
There is another reason I made the ship like this - I'll explain later.

I print the ship first (of course), then I print the bottle.
Here's the bottle being printed just before the ship is inserted:
As the bottle starts to get thinner it is time to insert the ship.
It just about fits past the print head, but only at some point during the
rotating movement of the head. I have to dump it in quickly otherwise
the print head catches it, resulting in a ship wreck.
When I get it right it looks like this:
When the bottle is done the ship is locked inside. Hey presto !
I decided not to make any special instruments to glue the ship down
inside the bottle. The fact that it rattles around inside seems more
intriguing... and it saves a lot of work.

The lens effect of the layers in the bottle (single wall, 0.4 mm thick,
layer height 0.2 mm) does blur the view inside, as you can see.

However, there turned out to be an unexpected effect: viewed from
certain angles, the (blurry) ship seems to be hovering IN FRONT of the
bottle, like a hologram. Quite freaky. Pity I can't show you here...

The ship-in-a-bottle is just one of the cool 3D prints that can be found
at Printed In Space.

More about ships and bottles in the next blog:


In past centuries ship-in-a-bottle makers had few possibilities to
connect with fellow enthusiasts. With the advent of internet these
craftsmen have now connected globally, showing their fabulous
creations to each other and the rest of the world.
To see some amazing pieces, I strongly recommend having a browse
through this website:

But DO come back afterwards to read part 2 of this blog: