# Design a mechanical part with Autodesk 123D Design

Let’s dissolve the boundary once more!

Here will be a quick but complex 3D mechanical modeling project you can use to practice your skill in 3D using any software you find handy.

Although this would have been a nice practice exercise for AutoCAD users, We will be using Autodesk 123D Design in this sessions, may be we will come back to this same design later using AutoCAD.

## Mechanical part in 123D Design

Here is what the finished design looks like in 3D

And below you will find all dimensions you need to know to replicate the design with accuracy.

Without further due, let get into it

#### Step 1

As usual  we will start with the 3D sketch we judge the most convenient to help propagate sketches into 3D. It depends on how you look at it.

I first need to get this sketched

#### Step2

Use the offset command to create other shapes.

#### Step 3

Here is what you should be left with after the previous stage

#### Step 4

Extrude both shapes in opposite directions, the biggest one by 8 and the smallest one by 24. (You might need few steps before 123D Design allows you to extrude both independently. You may just decide to copy and paste, tweak it a little bit before joining both object again)

#### Step 5

MERGE Both, and FILLET the upper edge by 20 and flat edge by 2.

#### Step 6

Turn the object on his belly, use the previously created sketch and the FILLET command to create the following shape.

#### Step 7

Here is what you need to have

#### Step 8

Extrude the shape created in the previous step by 24 inwards.

#### Step 9

Delete the 2D sketches and FILLET the inside edge by 12

#### Step 10

Create a cylinder and place in on the top of the whole.

#### Step 11

Move the cylinder downward by 16, and merge the whole.

#### Step 12

Place a cylinder of Radius 15 and height 5 on top of the previous cylinder

And create a cylinder of radius 4, longer enough to help create the circular hole in the middle of the previously created cylinders

#### Step 13

Merge the whole except the last created cylinder, and subtract the latter from the whole.

#### Step 14

Do the same to create the other part of the design

#### Step 15

FILLET necessary parts of the object to complete the project.