Parametric memory card holder / case (SD, MicroSD and others), extremely compact and lightweight, with FreeCAD source.

Purpose.

I'm quite satisfied with the C001 Micro SD card holder and case at home but I found that it is too big and heavy for bike touring trips where small size and weight are really important. So I designed an extremely slim and compact case for Micro SD cards. It is completely parametric in FreeCAD, and you can easily print it for any number of SD, Micro SD, Memory Stick, or even Compact Flash cards! Actually, you can store any rectangular things there! If you don't need it for traveling, you can use thicker walls and bottom to make it stronger.

For those who are not familiar with FreeCAD.

You don't have to edit the model in any way if the STLs that I uploaded are not good for your cards. You only need to change the values in the “ss” spreadsheet to customize it for your needs! Then click the part name in the Tree View ("card-holder" or “card-case”), select menu File-Export (to stl) and print. That's it!

Printing.

The card-holder is printed as it is. The card-case is printed vertically (rotate it in your slicer, the hole should be on the top). I didn't rotate it in FreeCAD to be able to visually control the changes in dimensions and tolerances in realtime while tweaking them.

For small cards such as MicroSD, print the holder at a slow speed to reduce printing artifacts and make the dimensions more accurate. If you print at a high speed you may need to increase the case x/y/z tolerance because the corners will not be as accurate as when printing at a slow speed and your holder will not go inside the case easily.

Tweaking and customization.

Before printing a holder for many cards, I recommend to test and tweak all the settings in the 4-cards version to save time and plastic. I found that the cards of different manufacturers have slightly different dimensions, so one card can be hard to insert into a slot while another card will feel comparatively loose in the same slot. You should find the best balance for your cards yourself. I added 0.23 mm tolerance to the X dimension of the slots and the way all my cards are inserted satisfies me completely. It may be different for your cards and your printer (it even depends on the printing speed!), but the golden value seems to be somewhere between 0.2 and 0.3. If only a few cards are too loose, you can slightly decrease the "fixer_angle" value to increase the pressure on the card by the top fixer. The less the value is, the better the fixation becomes, but your printer should be able to deal with overhangs. If you are not sure, keep it close to 45 degrees that all printers can print fine.

The following settings worked for me well (PETG, printed on Ender3 V2 at 15mm/s):

variable value comment

cnt 2 //columns: 2 or more
slot_x 11.23 //slot width
slot_y 15.30 //slot height
slot_z 1 //slot depth
bottom_z 0.6 //layer height below the slots
top_z 0.4 //layer height above the slot (fixer)
fixer_angle 40 //angle of the fixer above the card - degrees
walls 0.8 //walls width
end 3.7 //hole width to remove the holder from the case
lockpin_d 2.4 //lock pin diameter
lockpin_h 0.4 //lock pin height

case_side 0.4 //bottom side of the case that lays on the bed when printing
case_perimeter 0.8 //perimeter walls of the case
case_x_tol 0.2 //x tolerance (will become Z when printing)
case_y_tol 0.3 //y tolerance *2
case_z_tol 0.28 //z tolerance *2
case_finger_d 15 //diameter of the finger hole
case_lockhole_tol 0.15 //tolerance for the lock pin hole

Suggested values for SD cards:

slot_x 24.15 //slot width
slot_y 32.30 //slot height
slot_z 2.2 (for most SD cards 2.1 is better) //slot depth
bottom_z 0.8 (this is thicker than for MicroSD because the holder is bigger and bends easier) //layer height below the slots

The values that will be printed as Z axis should divide by the layer height. For example, if you set layer height to 0.2, your slot_z, bottom_z, top_z values should be 0.2, 0.4, 0.8, 1.0, 1.2, etc... If you need slot_z exactly 2.1 mm, you will have to use 0.1 mm layer height in the printer settings.

How to use this model for other types of memory cards.

The files micro-sd.FCStd and sd.FCStd have the same geometry but the values in the spreadsheets are different. You can use any of them if you need it for the cards with different dimensions - Memory Stick or Compact Flash. I just don't use them so I didn't make holders for them. The following dimensions were taken from internet but I didn't test them (don't forget to add 0.2-0.3 mm tolerance for X and Y):

Compact Flash (Type I): 43x36x3.3 mm.

Compact Flash (Type II) 43x36x5 mm.

Memory Stick, Memory Stick Select, and Memory Stick PRO: 50x21.5x2.8 mm.

Memory Stick Duo, Memory Stick PRO Duo, and Memory Stick PRO-HG Duo: 31x20x1.6 mm.

Memory Stick Micro (M2): 15x12.5x1.2 mm.

Any problems with the model tweaking?

Write in the comments, maybe I can suggest how to fix it.