Wayne was wondering:
I`d like to try to open many of my tanks and apc hatches how can I do this and keep the same dimensions? What do I use to replace the hatches and have them in the open positon? I would like to place some crewmen inside the turrets or hull of the vehilces. If the figures are to big what do you guys use for crewmen?

Sorry the pic isn't the best, but the command tank in this Sherman unit has an open hatch, and is manning a .50cal MG.
I have some SU-152s on my workbench now that I am painting up, and I have decided to do the command tanks with CO's unbuttoned.
To "open" the hatch, I have a small thumb-drill. I know several folks have Dremels, but I have looked at them and found them too pricey for my purposes. I bought an off-brand super-small power drill, but I've never even tried it. Rather, I stick with my tried-and-true manual drill.
I bought it at Radio Shack (an electronics gadget shop for those outside of US shopping zones), and it cost me about $4.00. It is about the size of a pen, and comes with 8 or 10 very fine drill bits in a few different sized. Cheap, very controllable, and handy. The advice of putting a pin-hole in first as a guide is very valid. Just twisting it between thumb and forefinger is all it takes to drill the soft metal of GHQ tanks. I wouldn't want to try it on steel plate, though.
For hatches, I just use the plastic that comes on the GHQ packs. I have who knows how many of them lying about ... I use them as paint-mixing palettes. I use the best/smallest scissors I can find at any one moment (with a wife and 4 kids, scissors seem to come and go at an alarming rate), and snip off a long thin rectangle of plastic. Then snip off a small square from this strip. Then snip off the corners. Then go around again, and again, snipping off whatever corners I find. After two or three round-abouts of snipping, it is pretty round. I can snip off one end if I want a flat hinge-face (as on the SU-152s). Super glue holds it in place just fine, and it can be painted-up with the rest of the tank. If I need any details on the upper surface (handles or periscopes) I suppose I could use the flash trimmed off of the sprues of small parts. But my eyesight isn't really up to that level of detail, so a flat-topped hatch works well enough for me.
For my figures, this time I'll be using US artillery crew. Empty handed, with arms in some interesting poses. I have "squeezed" their heads in my flat-headed tweazers to reduce the helmet's overhang, and will cut them off just above the waist to fit them mid-chest high in the open hatches. I am painting their overalls and helmets up in Polly-S "grimy black", dry-brushing with medium gray, and putting some details on their padded helmets with "night black".
I'll try to get some pictures up when they're done.