I have exactly one real fossil. It's actually really cool, but you know, these are expensive.
I wish they weren't, but they are. In this episode I'm going to tell you how
to make your own, that's good enough to fool people into thinking you have the right thing.
Depending on where you get things to print, you may or may not know about or have used
myminifactory.com - and even if so, you might not have noticed there's a section here called
"scan the world". This is a collection of over 17,000 real life objects, and there is
all sorts here.
Searching for fossil on myminifactory comes up with exactly what we want. I recommend
starting out with this one as it's a really nice sample and not too hard to orient correctly
for a good result.
Do bear in mind that you generally can't sell these even when printed or made into something
else - it's for your personal use only, check the licences though as it does vary.
I have shared my own print settings, I'll get to that at the end, but I want to talk
about orientation and support here. You need to aim for two things when deciding on orientation.
The first is that you ideally want the support touching parts that won't be normally visible,
OR parts whose details are not important. For this model I chose that to be the rear
just under the base of the shell. The second aim is to never have any critical details,
especially flat ones, on the horizontal axis. Due to the way 3d prints are made, anything
horizontal will have a worse finish with more evident printing artifacts than anything oriented
literally any other way. So in real terms I usually translate that as keeping the pointy
parts of a model pointing up.
So I found this orientation that seems to work. With regards to supports, I do increase
the support z distance a little between the top of the support and the part to allow it
to come apart easier, on larger more solid objects like this, you will find it really
hard to seperate otherwise.
You can use tree supports like I did on the large ammonite model, or you can use normal
supports. Really the choice comes down to a process of scrutinizing the preview. In
the large ammonite model I had to tweak the settings to give me a large brim on the supports
so that it would get good adhesion on the bed, it looked really strange when it was
laying down those layers but it worked really well.
Now, I have a future video on why you should change nozzles for long prints and no doubt
this will be an example in that video, because on a 0.4mm nozzle the print time was running
into two days, but with the right settings, and a 0.6mm nozzle, I managed to do it in
under 10 hours, which makes a huge difference as I didn't have to leave it overnight. So
watch out for that video and if you're not subscribed yet then maybe now's the time so
you don't miss it.
So with the printing all taken care of let's tackle the painting.
There is some secret sauce which you may or may not have heard of, it's called "gesso"
and it's used for...well...preparation for any number of substrates apparently. You can
buy it online or I got it at rymans here in the UK for a decent price for a lifetime supply.
It seems to last too as this pot is as old as I've been 3d printing and doesn't seem
to have dried up other than around the lid. Make sure you go for acrylic gesso because
acrylic paints tend to have good adhesion to PLA, plus I will be using acrylic paints
for the actual painting so it all works together well.
In terms of putting the gesso on, literally anything goes, just smear it on there. The
reason I used this is because it transforms the smooth printed surface into a rougher
stone texture which really does make all the difference especially when light bounces off
the finished product. If you have printed out your piece in a bold colour then you will
most likely need two coats of gesso, but if you printed out in black which I do recommend,
just one will do. White could go either way.
I think in a way the more scruffy and haphazard you are with the gesso, the better the result.
You want an organic stone finish and stones don't really care about being neat.
When the gesso is dry you just need to get some plain old acrylic paints. I'm not going
to teach you how to paint as honestly I don't know myself, but I found a process of smearing
on variations of black paint mixed white and brown, if you mix it loosely then you will
automatically get lots of shades as you brush. You can then dry brush on some highlights
and details at the end which I'm sure if you have any artistic abilities you can do better
than me, but really it's not hard to get a pleasing result. Again, if you spend any time
looking at a real fossil you'll note that nature isn't very neat, so the bar is pretty
low.
You'll probably find that if you do a half decent job it can be a new talking point when
friends come over, surprising them with how light your fossil is. Which reminds me, about
the settings. I have uploaded settings for prusaslicer for a 0.4mm nozzle, and 0.6mm
nozzle for cura. If you want to use the latter on a 0.4 nozzle then just change the line
width setting, but I did find prusaslicer overall better for this specific task because
its supports worked better for me, so I do recommend it over cura in this case. The main
settings that I want to draw your attention to are the 2 walls, 0.2 layer height and making
sure you have 3 top shell layers for a good thick top especially if it's curved. I also
increased the support x/y separation because by default the support is always too close
to the sides for me. You can increase the infill for more weight,
but I personally wanted to use as little plastic as possible, because wasting plastic printing
fossils seems sort of ironic to me somehow in a way I can't really verbalize. My profiles
are set up to be very lean, even the huge print only used 66 metres or so of filament
and is plenty strong and solid enough.
So that's it. Go forth and make fossils! Oh, and show me the results, I'm on all the social
medias now.
See you next time.