Wooden Toolbox, Part 1: Design Considerations

I've been volunteering at a local "Repair Cafe", where several volunteers try to fix stuff that people bring in.  The items can be anything from computers to little toy trucks, vacuum cleaners to jewelry - it spans a wide range.  So far, I've been bringing some tools in my red metal toolbox, but each time I use that toolbox, I have to dump out all of the tools that I definitely won't need and add a bunch of tools that I might need.  This is kind of a drag, so I though I'd make a wooden toolbox specifically for the repair events.

Here's a rendering of what I'm thinking.

Front View

Rear View

My initial thought was to have a drawer at the bottom, a lift-out tray in the upper area, and a space under the tray for more storage.  There is a horizontal divider that separates the drawer section from the upper section.  Since the drawer needs something to stop against when it is slid into its opening, the panel on the rear is full height.  But with the drawer opening on the front, the front panel is only partial height.

So here's where I had to scratch my head about the design of the toolbox.  It has to do with the joinery and wood orientation.  I'm planning to dovetail the box together, but I had to decide how best to do that, and how it might complicate the rest of the piece.

My first thought was to dovetail the ends with the bottom, in which case the grain of the ends would run vertically.  Alternatively, I could dovetail the ends with the front and back - here the grain of the ends would have to be horizontal.

I didn't like the second idea because if the grain on the ends was oriented horizontally, a good jolt to the handle could easily split off the top of the end pieces.  I'm making this out of soft wood and I don't think it would be strong enough in that orientation.

So I chose the first option, with the ends dovetailed to the bottom so the grain of the ends will run vertically.  This also simplified the joinery of the horizontal divider to the ends - the grain will be compatible and I decided to use multiple through mortises and tenons at each end.  That left me to figure out how to attach the front and back panels.

Front panel attachment

It's a little hard to see in the picture, but I've put a groove near the front edge of the horizontal divider, as well as on the vertical ends, that will house the rabbeted tongues on the front panel.

For the back I did the same, grooving the bottom and end pieces to house the tongues of the back panel.

Back panel attachment.  Note that I had to make the 
horizontal divider narrower to allow the back panel to fit.

Putting the groove in the bottom forced me to adjust the dovetail spacing.  The groove will show on the outside at the ends of the bottom, so I moved the rear-most tail in a bit (and adjusted the other tails accordingly) to allow the groove to fit fully in the end pin.

A couple other notes here.  In the first picture above, you can see the upper tray is not the full length of the interior of the toolbox.  This is so I could fit my battery drill at one end standing on the horizontal divider.

Lastly, I'm making this mostly out of reclaimed pine/spruce/fir.  The thickness of most parts will be 5/8" to give a compromise between weight and strength.  The horizontal divider will be 1/2" thick.  The handle will be 3/4" thick oak - with the curve in the handle, I didn't want to risk a break due to lack of strength of soft wood.

I'm interested in feedback on the design.  Do you have any comments on how the front and back panels could have been attached differently?  Also, for the drawer shown in the first picture, I need some way of keeping it in place (and not sliding out) when it is closed in place.  Any suggestions?