Part 1
ok…..class is in session
This Post is made so NOONE has to EVER ask in chat again HOW to build an OS. It is against the rules.
However, information is sketchy at best out there on the NET and I’d rather take
the time to build this tutorial than to have someone post badly done trash to this forum.
PLEASE take the time to do MORE research on the subject if you are indeed serious about building.
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How to build an OS using VirtualBox
NOTE: Updated 4-10-2021:When building, use VHD for hard drives even though illustrations show VDI.
Grab a CLEAN unmodified version of windows 10
Open Virtualbox and make a NEW entry. (Virtual Machine or VM)
Give that VM a DYNAMIC hard drive of 100gb (dynamic is set to 100gb but only uses space as needed so the whole 100gb isnt used)
Give that VM a 2nd DYNAMIC hard drive of 50gb and name it WIMS
Memory for VM – 4096gb (Your availability may vary)
Cores – 4 (your availability may vary)
Heres my setup in pics, easier to explain. The only settings I change from default are shown in images, so if you set yours up the same way as shown, it should work same as mine. My VM is named Windows10Builder.
When Virtualbox is setup, load the clean win10 and install as you normally would.
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When it gets HERE, do what the PIC says do.
PC will boot into AUDIT mode as administrator. You can use it just like a regular PC. Here is where you add any and all software, windows updates,
and any customisations you want to do to the system.
NOTE: I have an ISO I created with ALL my customization utilities, themes, etc. (BUILDER.ISO) When I build a new OS, I can just load the ISO and use my tools over and over again with each new build.
NOTE: I made the WIM drive 50gb on MY config so it could hold both the newly created .WIM file, as well as ALL my customization tools so I dont have to load the customization ISO every time.
This is done by loading the BUILDER.ISO in the VM CDROM then just copying over to the WIM drive.
The 1st thing I do is rename my C:\ Drive to WINDOWS and my D:\ Drive (or whatever drive the 50gb is) to WIMS (this helps later with the build process)
THIS will be on the screen, you can close it out as long as NO boxes are checked. When you reboot, the machine will always boot back into
audit mode and THIS will pop back up on the screen. You can reboot machine as many times as needed and it will ALWAYS boot back into
AUDIT mode as ADMIN.
When you are finished installing software, updates, and customisations, run the DISK CLEANUP utility located in the start menu. I checkmark ALL
the boxes, and it takes about 2-5 min. IF you have installed windows updates, the process can take up to an hour to clean out the older packages.
When you are done with EVERYTHING and have customized to your liking, and want to finalize your windows:
1 – Make sure the clean version of windows you installed from is loaded in the VM CDROM
2 – Make sure its ENTER SYSTEM OUT OF BOX EXPERIENCE (OOBE) , Checkmark the box GENERALIZE and SHUTDOWN click OK
You will see this on your screen for about 3-10 minutes depending how big your build is.
Machine will SHUT DOWN when finished sysprep functions.
Congrats, you have just finished Part 1 of building! Now to Part 2!
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Part 2
NOTE: Make SURE the clean version you installed from is LOADED in the VM CDROM
Now comes the fun (not) part. VERY time consuming. Restart the VM and when the PRESS ANY KEY TO BOOT FROM CD pops up, HIT a key, ANY key, and it will boot to Win10 install. When it get there, do as show in the following pic. Hit Shift F10
A command prompt will popup with X:\SOURCES at the bottom.
1- Type in DISKPART and (enter)
2- When diskpart is loaded, hit LIST VOL (enter)
This window will now popup (this is mine, yours may be different, but you will get the idea)
The drives will be named. Look for the WINDOWS drive and WIMS drive (the ones we renamed at the start of the build) and remember their drive letters or write them down if needed.
After seeing where your drives are. I want to capture to the WIMS/D-Drive and the disk I want to capture is WINDOWS/C-Drive
NOTE: YOUR drives may or may not be C and D, they may be F and G, thats why we rename them at start of build to WINDOWS and WIMS
so we know which is which.
Type this command, with spaces before EVERY /
NOTE: REMEMBER to change the IMAGEFILE drive to the WIMS drive letter and the CAPTUREDIR drive to the WINDOWS drive letter.
Press ENTER
This will run for FOREVER it seems. Usually about 20-60 minutes depending on the size of the build AND the speed of your machine and hard drives.
When it reaches 100% and file is saved, close down the VM totally.
Yay!!! End of Part 2
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NOTE: Updated 4-10-2021: Use VHD Attatch or VHD Manager, and mount the WIMS VHD (where you saved the INSTALL.WIM). Once mounted, copy the INSTALL.WIM to hard drive and then dismount the VHD. Once done, you can skip to part 4. This is just a quicker way of doing it. Nothing wrong having another VM made to retrieve the WIM file though. Redundancy 
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Part 3
I have a Win7 VM made just to get to the WIM files I create. I load it and add a 2nd Hard drive to it. instead of creating a NEW hard drive, I choose EXISTING hard drive, and choose the WIMS hard drive I made in the Windows 10 build.
NOTE: Make sure you have installed the VirtualBox Guest Additions when you first build this Win7 VM or install it anytime afterwards, otherwise you wont be able to create links to REAL hard drive.
1 – Add links to REAL hard drive (under shared folders)
2 – Boot the VM and navigate to the WIM folder and there should be your SAVED install.wim.
3 – Copy install.wim to your REAL hard drive and shutdown your VM when finished.
Yay!!! End of Part 3
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Part 4
1 – Make a directory of choice, lets say for example D:\BUILDS
2 – Using 7zip (or other) open the CLEAN original WIN10.ISO and extract it to the D:\BUILDS folder
3 – Go into that folder and there will be a folder called SOURCES, go in there and DELETE the install.wim or install.esd
4 – Copy YOUR new install.wim into the SOURCES folder.
5 – install.esd is the same as install.wim, but is smaller due to better compression. when building, you can ONLY work with .WIM files, so if you want to leave it as .WIM you can, or if you want to make the build a little smaller, you can convert it to a .ESD file. Generally using a WIM the ISO will be about 5.5gb in size. when using a ESD file the same ISO will be about 4.2gb, so it does save space and download time for users. Thats really the only advantage of using ESD over WIM. If you ever want to change anything in the future inside the ESD file, you MUST convert it back to WIM first.
6- There are NUMEROUS utilities out there to convert to .ESD If you want a smaller overall ISO, then use one of them. REMEMBER, you MUST use WIM files for ANY customizations though.
Only AFTER the customizations are finished can you convert to .ESD and have it work.
Creating the ISO
Install and open up WinReducer for Windows 10
Press START
Choose FOLDER and then navigate to folder where you extracted windows files to and click OK.
After hitting OK, WinReducer will load the files it needs to work with.
WinReducer will finish loading and then come up with options for just about everything.
Up to YOU to do the homework here on what you want installed and or customizations added.
NOTE: You dont need to do ANY customizations unless you want to change/add some things like custom boot and install screens.
You can hit FINISH (upper right corner) now and new ISO will be created just the same.
When you are finished customizing with Winreducer, hit the FINISH button located upper right corner.
Hit the APPLY button in the middle of the screen and hit YES to continue.
All changes will be applied at this point.
Click the Save in an ISO file radio button and choose WHERE to save the file, NAME of the file, LABEL of the file, and choose BIOS or UEFI or both.
I always choose UEFI & BIOS for best results on different machines.
Hit SAVE and then YES to continue. WinReducer will now create a BOOTABLE ISO of your new OS!
When finished, THIS notice will be given.
To test new build, Start Virtualbox and create a new entry (like earlier in this tutorial) and run thru the whole install process of your NEW OS.
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BE PREPARED FOR FAILURES!!!! Guaranteed you will have SOME builds fail and have to redo it a few times before it finally takes hold.
Ive had builds done in 1 hour, and Ive had builds take me 3 days. Just dont give up if you are serious about being a builder.
There are a LOT more things you can do once you get the hang of this. Experiment with different building tools. Some do more than
others, and the customization level is higher, but also requires a lot more knowledge as well. Good Luck!
