Hi TaranQ - as JTB mentions, there isn't a way to directly resize the hole itself, but one way is to use additional boolean differences or unions.

I wanted to let you know about one other technique which may be useful in this situation - it is possible to erase a hole and repair the original surface at that location. This can sometimes be a nice way to keep your model very clean, if you try to patch holes by using boolean union it will work but you may be left with a type of patchwork of surfaces instead of just a clean simple surface.

Here are the steps to erase a hole and restore the original surface.

Here's a hole:



The first step is to erase the side surfaces of the hole. You can select a sub-surface of a larger object by doing a second click on it after the larger object has been selected by a first click. Edges take precedence when doing this sub-selection so to select a face you have to pick it in an area not next to an edge - you often may have to zoom in a bit so that the surfaces are larger on the screen to make this possible. Once you select a single surface instead of an edge, you will be in surface-only selection mode, so it will be easier after the first one is selected. You also need to rotate around so that you can see the 4 different surfaces. With the side surfaces selected it will look like this:



Now hit delete - this will remove those surfaces, leaving empty space with unattached edges:



Select the open edges (this is again with a second click on the object after the first click has selects the whole object).



Now hit delete again to remove these trimming edges, and your hole will be erased and the original surface of the object will be restored there.

You can remove trimming edges of a surface by using delete, but only when they are not attached to anything, that's why the side surfaces need to be removed first.

After you have restore the surface in this manner you can now use another boolean to cut your new hole out.

In future versions I should be able to add more options for doing this kind of thing more automatically, for instance it could eventually be possible to enable dragging the hole around without erasing it first, or using history to change the size of the object being booleaned. But for V1 these won't be ready so the "erase hole" technique is what will work for right now.

- Michael