I have many different sizes/shapes of X-acto blades that have come with various sets I have bought. I got sick of having several different cases with blades, many of which could only hold one blade per spot because they used a ceramic magnet that wasn't that strong. I made this to hold a wider variety of blades, with room for multiples of each blade.
The tension is made using a printed piece of 910 Alloy Nylon and folding it. This can also be made by printing the same design on paper and using it as a template on a soda can or some similar thin metal then folding the tabs over. I had the 910 Alloy available and it was easy so that is what I went with.
Hatchbox and Taulmans PLA and 910 Alloy Nylon
I only used supports so the front cross brace that holds the blades against the spring would be supported so it is a very thin front and back support that are easily removed.
Bend the tabs of the "springs" and put the long parts back to back, tabs facing away and up then slide the long part down into the center slot of the holder until it rests on the center wall. Check your tab tension, heat or further bending may be needed to get the right tension.
Optional: I wrapped the area below the cross bar in clear packing tape just to give a kind of window to see the blade style in but also keep stuff out.
I did this really quick in Tinkercad using a few rectangles and copying them. More/wider/thinner slots can easily be added but this was more than enough for what I needed at the moment.