The Illustrator rectangular grid tool can be found in the toolbar under the line tool. You can, of course, also set up your own customized toolbar and add it to that to make it easier to access or just use the shortcut to quickly find it (the image shows a back slash but this can be changed if you wish)
Apply it by selecting the icon and clicking on the art board and dragging from the top corner and setting the width / height as required and releasing the mouse. The end result is a set of basic lines forming the artwork. You can set the size of the stroke as well as the weight as well as the fill of the design.
Double click the icon or press return and set the dividers (horizontal and vertical) for the rectangular artwork. You can set the width / height etc though generally I just define it as I draw it but it is useful if you wish your artwork to fit in a particular size format say 100 x 100 etc. Set the dividers and the skew. The skew, I hardly ever use but it can create some interesting designs.
You can set the horizontal to 0 and just get vertical divider lines. You can set the vertical to 50 or so to create a powerful set of 50 lines in seconds.
You can set the horizontal to 20 and set the vertical to 0 etc
Perhaps not one that I use a lot but you can create some interesting designs using the skew with the tool, vertical and horizontal. Must admit, I rarely use this option but it can be useful to create all kinds of unique designs that would be tricky to create manually. You can skew one or the other as well as both and skew it to the positive as well as the negative (or you can just rotate the design as I generally do)
Select the generated artwork and then go to the object menu and ungroup. You can then select the frame around the art and remove it
You don't need to keep the frame around the design, it is a rectangle and can be un-grouped and deleted to create an open design or hash design
You can also move the lines. You can select any of the lines in the design and move them so they do not have to be totally uniform. You can also select any of them and just delete them as well. To do this, you first need to go to the object menu and ungroup or instead double click the object and enter isolation mode and then select and move, Another option is to use the layer panel and select them there and move them or re-color them or add effects to them etc, they are just basic paths. You can also then change the stroke etc of the lines once you have un-grouped them, you can change the width, change the color, change the opacity etc
With the artwork selected go to the object menu and envelope distort and make with warp and select a warp preset. The result can be expanded via the object menu expand
You can fill the whole thing by just changing the color of the object, go to the tools box and select the fill color you wish to use. If you want to re-color individual ones then use the live paint bucket tool found beneath the shape builder tool in the tools box. Hover over the individual cells and change the colors from the swatches panel via the left and right arrows
You can use it as a single design but you can also join them together with different horizontal and vertical settings. All kinds of combos can be made as all you need to do is change the horizontal and vertical settings and then draw out the artwork so it matches the sizes (in the end) of the others unless you want uneven edges to your art. You can then group all the artworks together via the object menu and group
You can also take the above and then combine those together in all number of ways to create very complex and elaborate lattice designs in seconds
The tool can also be used with the tilde / grave key to create multiple objects very quickly. Start drawing the design and then hold the key and then you will see a mass of paths. Find out more about how to use a variety of effects in the application via our effects section.
You can create a design and then go to the object menu and repeat and radial (as well as the grid and mirror). You can change the number of instances as well as radius and you can also double click any of the artworks generated by the repeat feature and then modify the design in isolation mode. You can also use the repeat feature to create a quick frame design based on these paths. You can also use the objects in combination so you can have a radial as well as mirror combined and you can also still edit them as they are still live
Once you have used the tool, you may wish to remove part of the design say a circular center. You need to expand the design via the object menu (so set the stroke to something other than 0) and then go to the pathfinder and click the unite for all the lines. Draw a circle on top of the design and now subtract both and go to the pathfinder and click the minus front button
Add an artwork to your current art board using the tool and then go to the appearance panel (window menu) and go to the right side menu and add new stroke and you will see the design now has a new stroke. Set the color for the new stroke and then go to the effect menu and distort and transform and the transform command and set the move values or the scale etc or the angle.