Google SketchUp has become one of the most widely used 3-D modelling programs. In part, this is because of its easy-to-use interface. It is also because, in addition to the Pro version, it comes in a freeware version that is almost as versatile as the Pro. SketchUp has a number of functions that make creating models easier. One of these is the ability to merge two or more objects to form a single one.
Open SketchUp. Select "File" from the menu at the top and choose "Open." In the dialogue that opens, locate a file that contains objects that you want to merge. Select the file and open it.
Triple-click on one of the objects that you would like to merge. This will select all faces and edges that are a part of that object.
Select the "Move" tool from the toolbar and use it to position the selected object so it overlaps the other object you want it to merge with. Do not click off of this selected object, or you will have to use "Undo" to start again.
Right-click on the selection and choose "Intersect." From the options, choose "Intersect with Model."
Click off the object to deselect it. If you now triple-click on that area again, you will see that both of the objects you used are now selected, proving that they are now one merged object. Repeat this for any other objects in the scene you want to merge and then save your work.