Creating A Movie Prop: Aliens Egg

[DiMarzio]

Hello again everyone! I hope I can some 3D enthusiasm from you again with this personal project I did for a good friend some time ago

The Goal

This friend of mine is a big “Aliens”-movie fan. He’s a skillful airbrush-artist and really wanted to have this movie prop, this particular “Egg” (that has been in different shapes and sizes throughout the whole series I might add!). Challenge Accepted!

Designing and Planning
I had a 3D Printer, it’s a UP! Mini with a whopping 12x12x12cm build volume and 200 microns printing resolution or layerheight. I wanted to give something bigger than that so that meant I had cut things up and assemble it afterwards. I decided I would print it in White ABS and not Natural ABS because that looks a bit more transparant. My friend was going to airbrush it so bright with is always good as a foundation since I wasn’t sure if he was going to use a primer or not. More about painting later on.

After giving it some thought I gathered lots of reference photo’s and found out there’s a lot out there regarding this “Egg”. I decided to go with something that would be cool to make and sort of unique but still recognizable, well, at least for the fans out there In Zbrush I blocked out the shape pretty quick, it’s not exactly an egg ofcourse but the whole thing is simple by design as you can see. The cool thing in Zbrush is that you can work in symmetry-mode(s) and quicly get a good shape. In overall, the whole thing took me maybe a few hours worth of designing and cutting it up about an hour or so. That’s why planning ahead is important with designing for 3D printing.

Early work in progress version…didn’t like that texture on it’s body

Final version…

Printing
The “Egg” itself consists of 8 big parts and the bottom circle around it is divided in 4 parts. For the “Egg”-parts I made so-called “keys” and “hole’s” so that once I printed everything, it would all fit just one way. Everything would line up exactly as on my screen. Ofcourse with big prints come great respons…uhm warping

I tried various options within my software that comes with the printer, and I thought it would save a lot if I would print it as a big shell. I could do that, having every piece of the egg, lay flat on it’s “flat side” but since I needed keys and holes in there, I couldn’t do this. I choose a hollow printing fill (similar to that 20% I see everywhere in other software).

I made sure I calibrated my printingbed after each 2 prints or so, just to be sure it would be ok. I printed this at maximum resolution, 200 microns.

This White ABS was just incredible I think…came almost like plaster-like!

Although I get excellent prints of this little printer, I still had the smallest bit of warping sometimes, just can’t help it. It didn’t matter. The whole thing was going to be glued up and I would fill in the cracks with some Gesso (which takes forever to dry I think…probably would use something else next time). It took me a few days to get everything printed but it was worth it! It almost pained me to give it away…

Glueing and putting Gesso on the edges to fill up uneven bits…

…and a bit more…

My lovely daughter with the whole thing for scale reference

After I gave it to him, he was really impressed! In the course of several months he would go over the model again, sanding it off very lightly, with very fine sandingpaper. Also use a Dremel-tool for polishing and sanding it a bit here and there. After he was satisfied he would go on and paint it. The pictures you see here are the last ones I have and he’s still busy with it. I really have to mention he’s a patient guy and REALLY takes his time, it’s more of a side-project for him.

Painting
My friend was going to airbrush it. For those who don’t know what kind of paint can be used; to be safe you can go with Acrylic paint. My friend used a solvent-based paint and that works just as fine apparently! I guess it depends a bit on what your goal is and what type of paint you like or most of all, HOW you want to paint it.

Pre-painting stage… All the scales you see were accentuated by Airbrush…lots of circles…lots…

Almost finished! I know what you think: that white on the viny/slimy things isn’t right! It’s a base layer for more color to come on top…it’s not finished yet. I like the sanding he did!

He used a brown color for the base layering and after that he spend hours accentuating the little “scales” on the Egg’s body. He did that with dark-brown, thus creating a bit more shadowy effect and giving the scales more depth. As said, I don’t have the latest pictures but it’s close to finish on these ones.

Hope you like this maker-tale! It’s the biggest thing I’ve printed to date…yet… I made some other stuff that I’ll share if people like this kind of thing.

[Alex3DHubs]

Awesome again! Is there any tips and tricks you would recommend when designing those keys? How’d you split up the model?

[DiMarzio]

Hello Alex3DHubs! Don’t know why I didn’t include that question in my post Unfortunately there’s no way for me to edit it again as far as I can see. Anyway, regarding you question; you can go about it in a few ways. The way I usually do it is within Zbrush.

Splitting up the model

• If I think my model is finished and ready to be printed, I merge all sub-tools (separate objects) into one.
• With Dynamesh I can turn it all into one continuous mesh. So now I have a mesh that has everything fused together.
• With this new mesh, I make sure it’s Dynameshed (it should be ) and now I can slice it up one of the slicer brushes. You just draw a “line” where you want the cut and it will divide the object into 2 separate polygroups. For this model I had to make a few slices so I would have 8 separate pieces and they would all be there own object.
• After slicing I separate them into sub-tools, since they have their own polygroup that’s is very easy with the click of a button. Now I will Dynamesh each piece so it will have a nice continuous mesh and holes and errors will be filled up with new polygons. After this I will create the keys and holes.
• Optional technique: depends on the model a bit, for example a small figurine or something, or a model that you don’t need to slice up. I make a copy of this unified mesh, I use the Zremesher function on it. This will create a low-resolution mesh but with even polygon distribution, makes a really nice mesh. Then I will reproject the details of the copy onto this new mesh and divided it up until I have the desired detail back.

Creating Keys and Holes

• After I have the pieces all separate there’s going to be a bit of tedious work It’s a simple process of adding and subtracting objects. First, I will plan out how I want the objects to connect to each other.
• I have made an Insert Brush which consists of just one cube that’s a bit tapered toward it’s top. Doing it like this will sort of guide it in place when printed.
• With the selfmade Insert Brush, I will create a cube onto the flat surface on the desired side. I Dynamesh it again so it will be part of the whole mesh. Now I make a copy of this object because using the following technique will have it merged and if something goes wrong I can simply try it again, fast
• In the sub-tool pallette, you set to add or subtract. I choose the object with the key, to subtract with model above it which doesn’t have a key or hole. This way you will have the perfect hole for the key onto your mesh. What’s actually even better is creating a key where you want it, split this key off and duplicate it. Now you can scale the copy of the key a little bit bigger and use this version to subtract a hole onto the other mesh. Now you will have a slightly bigger hole since printing with plastic isn’t an exact science. Lots of factors will make the hole (or key) a fraction bigger or smaller. This way it will always fit and when you glue it it will never come off

Hope this explains it a bit, having a bit of Zbrush knowledge will come in handy. I know there’s another program called Magics (at least I think it was that program). You have the option to load your .STL’s and creating keys and holes but probably (or maybe) a more easier way.

[gabriela3d]

Another epic project, check this out @3DPrint_com

[mikeyzer0]

Really nice! As you were printing in ABS, you could have acetone-welded the pieces together instead of gluing, and used a slurry (ABS dissolved in acetone) as a filler. Of course this would have given a shiny result, but not an issue if you’re going to be sanding down. Very tempted to try this myself!

[DiMarzio]

Hi there! I’ve used the 'ol ABS Glue trick myself a few times, only I gave away my can of Acetone Besides, I got good glue and I wanted to try that Gesso stuff for filling up the cracks etc. Thanks for the input though! I’ve made the model available on Instructables, you can find the attachement there. I’m thinking I will upload it to Thingiverse too.

[gabriela3d]

Hey @DiMarzio, would you be willing on doing a separate post with ZBrush tips and tricks, to include all the info above? Just a thought, but I’m sure many will find it helpful. Cheers!

[DiMarzio]

Sure, I will even record some video of the proces if you. Where should I do the seperate post? This forum-like structure 3Dhubs is using, is a bit non-standard for me