Best enclosure for DIY decade resistor box?
This is a very tough question, and aesthetics criteria or IP rating criteria, or anything else these comes second.
Some considerations that you should made prior thinking to design an decades resistor box, or even a box with few resistors in series them separated by Terminal Binding Post Banana .
These are:
1) What is my test voltage?
This is critical if for example this is to serve at testing of Insulation tester (1000V upper range or more)
2) Which will be larger resistor in use?
Are you aware that only a few mid-priced Terminal Binding Post Banana they have as specification 500V Max and 100M Ohm ( as their own Insulation).
3) Aluminum or plastic enclosure?
By a plastic enclosure you may overcome electrical specifications limitations of most cheap low-end Terminal Binding Post Banana.
Example: 35V, 2A, unknown Insulation specifications.
By using an 100% Aluminum enclosure your gain will be totally noise free measurements, a yellow Guard Terminal Binding Post Banana must be added.
But you must be extremely careful in your selection of parts.
Decades switches specification, Terminal Binding Post Banana specification, and other details.