How to build a hollow sphere in Minecraft

Friday 15 Apr 2011 16:21
Plotz online voxel sphere generator

Plotz voxel sphere generator
for Minecraft

I wrote Plotz online voxel sphere generator to help people build hollow spheres made out of blocks in Minecraft. Using Plotz you can select the size of the sphere you want to build and see it on screen. You can then print out a schematic or use Plotz's on-screen step facility to see how the sphere is built layer by layer.

Start by visiting Plotz and follow the 'Take me to Plotz' link. Initially Plotz shows a 32 block high sphere. I'd recommend starting this size or smaller. This size took me a day to make (In Real Life) although I did mine all the materials myself. Use the arrows either side of the size to step up or down 1 block in size or type in a new size between 1 and 64 and hit enter to change it. Be patient if your machine is slow while Plotz generates and renders the sphere. Once you're happy with the size of sphere you want to build you can either print out a schematic OR work on screen.

If printing, hit the print button. Plotz will preview the schematic on screen. The various print options are well explained and mostly relate to saving paper. The ghost layer is by far the most useful option and is turned on as default. This makes sure you can see how each layer is positioned relative to the layer below. Adjust your options if required and then click Print. Choose your printer, set and printer specific options, start printing and make a coffee.

You might also consider printing to a file such as a PDF file. I've heard CUTE PDF is good for this but haven't used it myself. Printing to a file will allow you to bring the schematic up on-screen. This is especially useful if you have multiple monitors.

If you don't have a printer, don't despair. I actually found working on screen and stepping through the layers of my sphere very easy. Start by entering 1 in 'show up to layer'. Now use the arrow buttons either side of that value to step through the layers. The gold highlight clearly shows the current layer. Switch between Plotz and Minecraft while building using your OS hotkeys (alt+tab for windows).

Start voxel sphere

6 layers in with
dirt 'joining' blocks front left

Halfway voxel sphere

48 block high voxel sphere
half way done

Minecraft sphere in clouds

Close to finished and
in the clouds

Make sure there is enough room to build your sphere. I put down dirt 'posts' to mark out the width and height where I wanted to build. This way I made sure I wasn't going to end up having to dig out any mountains or cliffs that might be in the way. Also, remember that from ground level to the top of the sky is 64 blocks. Don't leave yourself short of space to finish your sphere.

Starting from the ground up is a no-brainer choice. Where there are no overlapping blocks between one layer and another, just use dirt blocks as 'joiners' and remove them later. I also used dirt with ladders for scaffolding as well as ladders. Always enter (and exit) from the top in case there are any creepers about and light up the inside with torches to stop skeletons and zombies spawning inside at night.

When building a layer I found it easiest to remember the stepping around the edge of 1/8th of the circle as a series of numbers in my head. Even when I built a 48 size sphere I never had to remember more then 4 or 5 numbers. Build each eigth towards another to make quarters. When they meet at the correct place you can be confident there's no mistakes. Before you know it, that layer is finished and you're on to the next.

I hope you find Plotz useful and please leave feedback here on my blog with any comments you have!

Minecraft sphere 2

Dirt and ladders

Minecraft sphere 3

Even at a distance a
48 high sphere is huge

Minecraft sphere 1

The finished sphere with
fancy end caps

Minecraft House

Modern house made using
Plotz as a guide

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17 May 2014 02:27 by Kevblog
I can't quite do 600, but the new HTML5 Plotz goes up to 256 blocks. You can find it at and follow the menu from there.
21 Apr 2014 04:58 by JackDaniel
Would it be possible to make Plotz go up to 600 because 128 is way to small for what i want to do.
19 Jul 2013 12:49 by Fingers Mahoney
@ThreeFlushLog or you could just build half the sphere.

btw LOVE the modern house kevblog. i may actually try something like that later today.
18 Mar 2013 03:29 by jaboi
great tool, very helpful. would love to see more designs put up
9 Mar 2013 05:22 by ThreeFlushLog
A very handy tool. Thanks tons for making it!

A nice tweak to the sphere tool would be to allow the user to remove the bottom, so has to produce a dome (currently half the sphere can be shown, but only by taking the top away, not the bottom).
9 Feb 2013 03:25 by pale_blue
This is an excellent tool and keeps getting better. I have two suggestions for enhancements that would be particularly helpful especially on larger builds:

1.) The total block count is good, but how about showing the blocks on the current highlighted level? This would help in resource and inventory planning.
2.) Perhaps mousing over a yellow block could provide relative (x,z) coordinates? On an odd diameter, the center would be (0,0), but with an even diameter, the logical center would probably need to be (1,1)(1,-1)(-1,1)(-1,-1).

Keep up the great work!
15 Dec 2012 04:52 by hungmanmoojoo
would it be hard for you to make a saucer generator aswell? or elliptoid saucer for that matter?
anyway.. thanx for thsi wonderful tool
20 Nov 2012 12:04 by Lung Zatar
Same for me, looking for a 192 sphere diameter ... And plotz is by far the best, but only 128...
14 Oct 2012 01:30 by S1D3WYZ
Would REALLY appreciate an update to LARGER sizes... want to build a 150+ diameter base, a bigger Golden Gate Bridge

also, RADIUS (as an addition or replacement) would be really nice get layouts that accomodate certain chest/door placement configurations.
14 Jun 2012 06:43 by fireside
im making a large dome in minecraft with a diameter or 140 blocks. and i cant find anything that will render the sphere without crashing my computer. the 128 diameter sphere works great! but i need it a little bit bigger! if that isnt a problem!
5 Jun 2012 09:48 by jables225
This is fantastic! i'm so glad i found this. now i can finally build Laputa without much trouble.
27 May 2012 07:35 by Kevblog
Thanks for the comments about Plotz being down. I can only apologise for this as it was my own stupid mistake that took it down. Its now working again.
25 May 2012 02:15 by AwesomeBro360
Just want to say that this is an extremely useful site! It alllows me to make amazing buildings alot easier. At the moment Im making a giant underwater dome sort of area, sort of like a underwater topia or something of the sorts. Only problem is I haven't been able to get on the site for a while! Is there something with the servers or is there just a problem otherwise, idk. Anyway I hope that it will be repaired soon so that I can get back to building.
23 May 2012 01:25 by mnky
I would just like to say what a great app this is - I have been using it recently but since about 2 days ago the flash box is grey and lifeless - i havn't found another generator that matches your block configuration and am a bit stuck atm
22 Jun 2011 09:05 by KevBlog
Thanks so much. This server rarely goes down, but computers being computers it can happen.
17 Jun 2011 10:35 by Morepork
I would just like to thank the author of this blog so much for this tool. I had a bit of a scare yesterday when all your sites went down, including plotz. I am halfway through a 64 diamter sphere and thought that I would be stuck at this point forever. Luckily it seems to be working again.

Thanks so much.
2 Jun 2011 03:48 by chousaru
nice work on the tower, i played around a bit with it, though i have yet to try an actual build. it struck me the other day that if you had the option of choosing hemisphere, it would cut the block number in half, and the user would simply have to reverse the layer build pattern for a complete sphere. of course, the hemisphere would need to include the odd numbered builds, e.g. a sphere that would be 255blocks (to include a single midpoint block rather than a pair), the hemispshere version would need to include the 'mid' layer. feel free not to include this comment on the site, it is a little rambling... :)
2 Jun 2011 01:42 by Vandigo
I found this at 3am last night, after failing to find a method I could understand for my project. For making a "small" globe to be suspended in my building, this is by far the most effective tool I've found, and I'm going to link it in my blog along with screens of my finished project.
16 May 2011 01:03 by chousaru
that's cool, looking forward to seeing what you come up with in the wizard tower dept. :) the towers i have built by hand have been simple circular cross-section type. the trickier bits have been how to finish off the top. inevitably it ends up as a kind of cone, usually made of glass...

as regards the sphere, thanks for thinking of revisiting that when you are ready too - no pressure..! ;)
16 May 2011 09:20 by Kevblog_Plotz
I'm currently expanding Plotz to do Wizard towers! After that I'll go back and look at sphere size. Have to say that Flash starts to slow down exponentially as width of spheres increases due to the increasing number of blocks on screen but maybe I can add a progress bar for those longer operations.
15 May 2011 01:18 by chousaru
hi there, nice app.

i need the sphere generator to go up to 256, so that i can use just the top 1/4 levels to build the largest habitat dome i can in Mcraft. any chance of increasing your upper limit to accommodate me? :)