Make a safe USB powered test tube light. (optional 3D printed end)

A very simple, but very attractive DIY test tube light that can use a standard rubber or cork bung with a hole drilled in it for the cable, or a custom sized 3D printed insert created from the customisable scripts below in this description.

The current this light draws is just 100mA (not 500mA as I said at one point in the video) which equates to about half a watt, so it will run for a long time from a USB power bank and will be a very light load for a plug-in USB power supply.

The materials are:-
A pack of test tubes from eBay typically about 18mm (about 3/4") by 200mm (8").
A string of copper wire LEDs with battery pack.
A 22 ohm quarter watt resistor
A cheap USB charging lead in a colour and style of your choice.
Some heatshrink sleeve (optional)
A small cable tie (optional)
A 3D printed end, a cork or rubber bung for the test tube.

If you use a cork or rubber bung you may need to drill a hole in it for the cable. Do so carefully as they are both very "snatchy" materials when drilling.

If using the 3D printed end cap you can copy the scripts below into openscad to create one in a custom size and colour. There are two scripts, one for a simple size checker and one for the full thing. Both have a single adjustable variable called diameter, which is the inside diameter of your tube or bottle neck in millimetres.
When adjusting the variable to something like 19, make sure that you leave the = and ; intact as they form part of the script. So you would change diameter=16; to diameter=19;

It's a great project. The end result is visually appealing and fully serviceable if you don't glue the end on too permanently.

This video is unexpectedly in just 720P due to a finger fumble while using the timelapse feature for the first time during the 3D printing. The video size options are directly above the timelapse speed settings.

If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
http://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's advertising algorithms allowing it to be a bit more dangerous and naughty.

Here are the openscad scripts. There are two of them.

//Test tube lamp size tester
//Change this diameter variable to suit the
//inside diameter of your test tube
diameter=16;
//The printed test tube insert will have
//end section 0.5mm thinner
//midsection size as entered diameter
//base section 0.5mm bigger
difference(){
union(){
translate([0,0,0])
cylinder(h=2,d1=diameter+2,d2=diameter+2,$fn=40);
translate([0,0,2])
cylinder(h=6,d1=diameter+0.5,d2=diameter+0.5,$fn=40);
translate([0,0,8])
cylinder(h=6,d1=diameter,d2=diameter,$fn=40);
translate([0,0,14])
cylinder(h=6,d1=diameter-0.5,d2=diameter-0.5,$fn=40);
}
translate([0,0,-1])
cylinder(h=25,d1=diameter-2.5,d2=diameter-2.5,$fn=40);
}

MAIN END ADAPTOR SCRIPT BELOW.


//Test tube lamp adaptor
//Change this diameter variable to suit the
//inside diameter of your test tube
diameter=16;

difference(){
union(){
//cable entry chamfer
translate([0,0,0])
cylinder(h=1,d1=8,d2=10,$fn=40);
//cable entry
translate([0,0,1])
cylinder(h=4,d1=10,d2=10,$fn=40);
//taper section
translate([0,0,5])
cylinder(h=15,d1=10,d2=diameter+2,$fn=40);
//tube insert
translate([0,0,20])
cylinder(h=14,d1=diameter,d2=diameter,$fn=40);
//tube insert chamfer
translate([0,0,34])
cylinder(h=1,d1=diameter,d2=diameter-2,$fn=40);
}
//main inner cylindrical hole
translate([0,0,20])
cylinder(h=20,d1=diameter-4,d2=diameter-4,$fn=40);
//inner taper section
translate([0,0,5])
cylinder(h=15,d1=6,d2=diameter-4,$fn=40);
//cable hole
translate([0,0,-1])
cylinder(h=15,d1=4,d2=4,$fn=40);
}