Why two rows of six
Twelve bits in one row need a strip close to 118 mm long. Folded into two rows the same dozen take up 60.6 mm, short enough to stand across the width of most driver cases and to sit in a trouser pocket without levering out. The cost is reach: the back row is harder to grip when the bits are short, so this page raises the block to 15 mm with a 2 mm floor. The pockets are then 13 mm deep, about half the length of a 25 mm insert bit, which leaves 12 mm of every bit standing clear to take hold of.
What to measure
Standard driver bits are 6.35 mm across the flats, and in practice most measure 6.30 to 6.35 mm. Measure the space the block has to go into before anything else: the inside width of the case, less a millimetre, is the limit for the 60.6 mm length. If it is too long, drop to five bits per row; the length falls by 9.6 mm for every pocket removed.
Clearance, wall and material
A pocket clearance of 0.25 mm gives a 6.6 mm pocket in which a bit slides in under its own weight and stays upright. A block that travels in a bag is better slightly tight, so that bits do not shake out: try 0.15 mm on a printer that makes accurate holes. The walls between pockets and around the edge are 3 mm. PLA is suitable, as nothing here flexes.
Printing
Print with the pockets facing up, flat on the bed, with no supports. The pocket floors are closed layers printed over infill, so use at least four solid layers under them or a bit dropped in hard will punch through. A 0.2 mm layer height and three perimeters are enough.
Outline drawing
Top view, to scale. Pocket centres are 9.6 mm apart along a row and about 10.6 mm apart between the rows.
Parameters the generator will use
| Setting | Link parameter | Value |
|---|---|---|
| Model | model | bit_holder |
| Bits per row | count | 6 |
| Rows | rows | 2 |
| Bit size across flats | across_flats | 6.35 |
| Pocket clearance | clearance | 0.25 |
| Wall between pockets | gap | 3 |
| Wall around the pockets | margin | 3 |
| Strip height | height | 15 |
| Floor under the pockets | floor | 2 |
All lengths are in millimetres. Outer size from these values: about 60.6 x 24.24 x 15 mm.
Open the generator with these values
This model needs the $7 licence key: one payment, one key, and it opens all five paid models. Get a licence key on Gumroad ($7)
The hex bit holder strip needs a licence key: without one the generator shows the model locked, lists the values from this link and fills them in as soon as you unlock. The fitted drawer organiser bin is the free model and downloads with no key.