STEP 1: DISCONNECT THE NEGATIVE BATTERY TERMINAL
- Navigate to C:\Program Files\Autodesk\Fabrication 2021\SDK\Samples\CSharp.
- Right click the FabricationSample folder and select Copy.
- Paste this folder in a working directory somewhere, it’s nice to leave the SDK Project unaltered for later reference.
STEP 2: COPY THE ADDIN BUNDLE
- Open the copied FabricationSample folder and navigate to the ACAD directory.
- Right click the FabricationSample.bundle folder and select Copy.
- Navigate to C:\ProgramData\Autodesk\ApplicationPlugins and Paste the bundle folder.
STEP3: OPEN THE PROJECT AND UPDATE THE REFERENCES
- Open the FabricationSample folder and double click FabricationSample.csproj.
- In the Solution Explorer, expand References. We can see that there are four unresolved References.
- Right click References and select Add Reference.
- Click Browse and navigate to C:\Program Files\Autodesk\AutoCAD 2021.
- Select accoremgd.dll, click Add, click OK.
- Repeat steps 3 through 5 for acdbmgd.dll, and acmgd.dll.
- Right click References and select Add Reference one more time.
- Click Browse and navigate to C:\Program Files\Autodesk\Fabrication 2021\CADmep.
- Select FabricationAPI.dll, click Add, click OK.

STEP 4: REMOVE THE AUTODESK PREBUILD EVENT AND BUILD THE SOLUTION
- In the Solution Explorer, right click the FabricationSample Project and select Properties.
- Navigate to the Build Events Tab.
- Delete the pre-build event command line text.
- Click File, click Save All, click Save.
- Click Build >> Build Solution.

STEP 5: COPY THE ADDIN DLL
- Navigate to the FabricationSample\bin\x64\Debug folder.
- Right click the FabricationSample.dll file and select Copy.
- Navigate to the C:\ProgramData\Autodesk\ApplicationPlugins\FabricationSample.bundle folder.
- Paste the newly built DLL file.
STEP 6: RUN THE ADDIN
- Open CADmep 2021.
- Type FABAPI at the Command Line and hit enter.
- The new DLL we built is not signed so we must verify the publisher.
- Play with the Addin!


OMG thank you for this.
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