The insert should hold the hook securely. Slots facilitate repeatable placement, and smooth foam requires careful puncture so it does not tear quickly. Don't stick the tip too deep and let the barb lock the fly in the material. For very small models, good visibility is important, so arrange by size, type or water layer instead of mixing everything.
Moisture is a major risk. Waterproof closure protects against outside water, but can keep condensation and wet flies inside. Use patch or a separate temporary drying site and do not store used models immediately on dry ones. After the outing, open the box, inspect the hooks for corrosion and let the contents dry in a ventilated place.
For walking by a river, choose a box that goes steadily into a pocket or a vest and can be opened with one hand without the contents falling out. The larger archive remains in the main luggage, and a select set is carried by the water. Label the boxes by type or season, but leave room for changes. Regular inspection of tips and materials is more useful than the accumulation of very similar flies. Check the closure after each fall or hard blow.
Organize the boxes through Muharnic fishing, the general boxes and binders, cases and bags and Fishing Instruments. Separate the worn set from the dry reserve.