Introduction: 3d Printed Medical Vein Finder

Picture of 3d Printed Medical Vein Finder

Hello there.My name is Alex , I am a military automotive engineer and my girlfriend is a registered nurse . Her job task is to take blood samples for further analyses from patients of all ages ( especially young ) . Her first day at her new job wasn't that great because she wasn't that experienced in finding veins, and while she complained, i googled up some solutions. Vein finders are common in western countries but here they are too expensive for us ( 100-150£ for one vein finder , and her income was standing at 200£ per month ) so i decided to make one myself .I found some ideas , articles but no instructions ( the one in Kenya for example) and then i found this link , but as a patient , i wouldn't want my nurse to use that on me because of its appearance. So I designed a whole series of them in the attempt to make it more patient - friendly , and i finally succeeded. I also made it in a way not to warp when printing with PLA , using blue tape , rubbing alcohol and the heat bed not active because i assumed it would be printed in areas that are poor and a printer with a heated bed would be more expensive .
Also this can be used in various countries around the world where they don't have medical equipment or money to buy it or professional staff is scarce . Now with the Zika virus , malaria and all sorts of diseases ... it's a helping hand.

How does it work. Well , light at 620-680 nm penetrates skin, fat tissue and oxygenated blood with ease but when it meets de-oxygenated blood ( what circulates trough the veins ), it gets caught up in there , thus resulting in a dark area. You will have to put the device on skin , search for a proper vein , aim it , and put the needle in that gap , in the vein. Very useful when working with anxiety suffering patients , children , patients that may cause them a drama if you try 2-3-4 times to get a sample of his/her blood.(btw sorry for my English).

Step 1: Materials

Picture of Materials

For this project you will need the following

- 3d printer with darker filament ( i tested green , purple and yellow , purple was the best , yellow the worst, green was ok )

- soldering iron and lead

- dremel

- on - off switch link

-1 M3 bolt ( not that long , 5-8 mm should be enough )

-1 M3 metal threaded insert link

- battery contacts for 2 AA batteries link

- 2 AA batteries( not in the picture )

- wire link

- 1 medical needle from a syringe

- 1 tweezers

- 1 nail cutter

- pliers

- glue

- caliper

- 10 cm of shrinking tube link

- about 15 resistors at 51ohm ( should be ok between 45 and 75) link

- about 15 red LEDs wavelength above 620 nm and not higher than 680nm because you won't be able to see the light at all and between (edited after more testing) 5000 and 6500mcd ( not higher it will have the same effect as facing a car with headlights on coming at night from the opposite side of the road and you won't see the veins, not lower , it won't enough power to penetrate skin efficiently the veins) link
EDIT: I did not use 15 leds or resistors only 11 of each . I stated 15 so that if some people wire the leds wrong and burn them , they would have a spare and not wait another week or so for resupply.

I used and you will find all the items required over there with ease . It's a great polish website , delivers all around Europe .

Step 2: Printing

Picture of Printing

Here are the files. It took my like 3 months to figure it out how to make it better. Now is safe to work with it..
It takes about 4-5 hours with sunhokey 2015 to print .
Use dark colored filament , I tested with yellow , purple and green . Purple was the best , green was ok , yellow was useless .

Download files from here (Zortrax library)

I used 0.25mm layer height because I want it done fast, if you want , you can get it done at 0.1mm , and it will look like out of the factory.

I used Catia to design it.

If you don't have a 3D printer , you can buy the prints from shapeways.
lid -
USE PLA as it's not toxic , don't worry , it won't break if you drop it , i made some design features to increase its strength.
Also. Lay down the blue tape , stick it well with a card ( i used my pharmacy card because I don't use it very often ) eliminate the bubbles under the tape. Spray your tape with alcohol ( 70-80%) but not much to soak it . let it dry for a minute then start your print but before you stat your print , click to make the brim about 12 mm wide. It works. You can use any method you like , hairspray and glass , or kapton tape , the choice is yours.

Step 3: Preparations(1)

Picture of Preparations(1)

While the printer......prints , your LEDs need their skirt trimmed . the hole in the vein finder is slightly larger than the diameter of the LED so it does not move around ( i had some problems with earlier models . trust me , you want your LEDs to sit put. )
Use your dremel and a sanding tip to trim them.
5.52 mm initial diameter down to 4.81mm ( hole diameter is 5mm )

Do this for all your 15 LEDs

Step 4: Preparations(2)

Picture of Preparations(2)

Second . When you want to solder the LED and your resistor , you will have to work in a veeeeery tight space ( in order to make the device usable in daily life , i had to shirk it . so ...while my girlfriend tried her needles on me with a earlier bulky model , i had an idea . why not wrap one end of the resistor around the needle , pull it put , and then solder it around the LED? ( the soldering part comes after placing the LED in the 3d printed body )
Do this for all your 15 resistors.

Step 5: Finishing the Printed Body and Mounting the LEDs

Picture of Finishing the Printed Body and Mounting the LEDs

But first , we have to remove the printed body from the printing table . Btw , I usually use blue tesa tape + rubbing alcohol . it sticks so well that it's annoying to remove , and then , I use dental floss , peal the skirt a little , then put the dental floss underneath and get that print out of there. Then , we must polish the LED places from underneath as blobs may get formed during the print.
Then , we must mount the LEDs . The LED has a longer leg and a shorter one . Put the longer legs closer to the center , and the shorter legs outwards.

They will be connect as the diagram shows.

Step 6: Soldering 1

Picture of Soldering 1

Bend the longer legs with the tweezers and solder them together.

Place the resistors like in the pic on the outer ring (the shorter legs) , solder the resistors to the LEDs and then cut the extra length of the leg with the nail clipper . Place a 3-4-5 mm shrinking tube at the LED-resistor area , and shrink it with your soldering iron ( that's how i do it ).

While the soldering iron is still hot , place your metal insert above the hole and gently push it down.

Then , solder the resistor legs one to each other. it should look nice like in my pic.

Step 7: Soldering 2

Picture of Soldering 2

Place your battery contacts afterwards and bend their tail inwards . I lock the contacts in place melting the plastic around it with my soldering iron but you can glue them . Solder the negative pole of your batteries the outer ring . Solder one 5 cm wire to the inner ring , pull the wire trough the switch gap , and the other end solder it to the switch on\off . Another 5 cm wire to the positive pole, pull it trough the hole and then solder the other end to the switch. I recommend you should isolate your switch legs with shrinking tube , and that you should place one 5 mm shrinking tube on the wire from the inner ring and from the positive pole before soldering the wires to the switch . Mount the switch into place. Mount the top plate into place and glue it shut.

Step 8: Finish

Picture of Finish

It's done. All you have to do now is get some batteries , place your battery cover and close it down with the M3 bolt.

If you have any questions , please send them to here : either ( my gf ) , or ( myself )

Step 9: Using the Vein Finder

You light it up , put it on the pacient's arm perpendicular to the vein's direction , find a good vein , flip it paralel to the veins and put your needle in that U gap . Simple as that.


DavidW730 (author)2017-09-04

I enlarge the battery cap abit to make it snug fit... Love this design.

AlexS154 (author)DavidW7302017-09-05

Looks nice and neat! Unfortunately, not all people have such tunned machines as yours but congrats on your build :D

DavidW730 (author)AlexS1542017-09-05

If you don't mind I can upload the remixed battery cover to thingiverse for others to download. Bcos your thingiverse listing is under Non-derivatives license, so I didn't upload it.

*Btw my first printer also sunhokey i3, and I first saw your design was in Sunhokey facebook group. Thanks again for your great design.

AlexS154 (author)DavidW7302017-09-05

Sure you can. I was referring to the led circuit to not be modified without testing first so that people won't flood the Internet with non working designs

ParkerT3 made it! (author)2017-06-18

Thanks for posting this! Awesome project and your guide was very well done

AlexS154 (author)ParkerT32017-06-26

nicely done!

mrsingh1 made it! (author)2017-04-13

Cheers, this is a god save, no more me being a pin cushion when drawing blood

AlexS154 (author)mrsingh12017-04-21

nice color! ideal one tbh :)

caitlinwood (author)2016-05-30

Hi This is a great project. I was wondering if you have made any with rechargeable battery pack? Im not an engineer and was wondering if it was possible.

AlexS154 (author)caitlinwood2016-05-31

here are some pictures.

Hongduc (author)AlexS1542016-10-24

Can you sent me the update version of your veinviewer to, thanks you and sorry for my english :(

AlexS154 (author)caitlinwood2016-05-31

i have a house full of prototypes with batteries bigger smaller , rechargeable any size shape form and colour . the one posted here had the best results you can get at a low budget with easy to find materials.

RoslinaR (author)AlexS1542016-06-12

Hello Alex, can i know what type of rechargeable battery you used for 9-10 LEDs? and how the connection of the circuit?

AlexS154 (author)RoslinaR2016-06-12

the rechargeable battery :
circuit is almost the same , only added a jack to connect it to an external charger

AlexS154 (author)caitlinwood2016-05-31

I did one that was rechargeable but the cost of the rechargable battery pack + connectors + 5volt source added to the total cost and also made the device a bit bigger

caitlinwood (author)AlexS1542016-05-31

Thanks so much.
I was also wondering if you had tried with a different amount of LEDs? I now in some of the "real' vein scanners they have up to 30 LEDs. Would that make the veins easier to see?

AlexS154 (author)caitlinwood2016-05-31

Havent tried because they use smaller leds (3mm i think) and i use 5mm ones. If i increase the number with 5mm ones i would have to increase the led "ring" way beyond the effective area. Using 3mm ones would mean more time building , less space and more qualified personell building the device because you would have to put 25.30 leds in the same space you put 11 bigger ones. The ones made by companies are manufactured in part by machines and part by human hand

ArtH12 (author)2016-08-31

Hi there, we only have LEDs up to 2800 mcd in luminosity at 660nm. Can i use them instead and just double the number of bulbs? Thank you

AlexS154 (author)ArtH122016-08-31

no , because they need the power to penetrate . using many more will make a hazy , foggy , blurry light that will not penetrate the same amount of fat/skin

lucpet (author)2016-08-30

After all the trouble I went through to make this, the lights seem to get weaker as you go around the lights. They start bright and end up barely glowing. Anyone else get this, What might I have done wrong any suggestions?

AlexS154 made it! (author)2016-07-09

Made for the hospital staff as a gift

Cikobaba (author)AlexS1542016-08-19

Hello. I'm sorry about my english a question you can sell me one because I neither 3d printers have otherwise know nor excessive electro . Who yes , write me please. . I work in an honorary blood decrease that would be extremely helpful . Thank you.

spyder30 (author)2016-06-22

Thanks for the plans. I purchased from your supplier from the links but appear to have a power drain on some of the LEDs. It may be from the resistors if they are too strong a resistor but I was wondering if you have come across this problem before? The one side lights up bright the other dim, if I switch power to opposite sides (but correct anode cathode position) the new side is the brighter side, so we can rule out wiring.

Thanks again for the Awesome device. My friend printed the case and I did the electronics (I suffer from a condition that puts me in the ER up th 6 times a month so this will help until they finally get around to giving me the port line).

AlexS154 (author)spyder302016-06-25

if you have a voltage meter try to get some readings from your batteries. can you share a picture of the case please?

spyder30 made it! (author)AlexS1542016-06-25

New batteries checked on my breadboards voltmeter so no the best, but I believe that when LEDs dim in parallel it is cause by a current drop (right?). I considered inconsistency of LED output (due to production standards) but since it's power supply side dependent on which side is lighting brighter (because I did switch it around and the opposite side light brighter), I am considering the resistors may be too high a resistance (I checked the circuit without a switch so there is no resistance there fowling things up). Thanks for he help. I too was a military electrician, wish I knew more about engineering though. Never ins the breadboard in the photo.

AlexS154 (author)spyder302016-06-27

i have never crossed this problem (partial dim) even with larger ohm resistors. you should try to make 1:1 the project(i fear a shortcircuit on that breadboard) , no try , no gain.
btw , i know next to nothing about electronics (basic stuff and some things you find in cars like the alternator or how a battery works) , it.s the mechanical part i.m specialised in

spyder30 (author)AlexS1542016-06-28

Thanks. The breadboard was just used to hold up the project for the picture. Well, in parallel resistors drop current before each LED which could cause a dimming across the line (I may have got some bad resistors, or these batteries may be old and not putting out enough power even though they are new). I did set up almost the same circuit on that breadboard (parallel with same exact resistors and LEDs but only like 7 and still had a drop in brightness). I am just going to run my resistors through my multimeter and the LED stats through the calculations. I am just adding this for anyone who may be using this convo to troubleshoot, you no longer need to respond Alex. If I figure out the problem I will get back to you. Thanks

spyder30 (author)spyder302016-06-26

*Never mind the breadboard in the photo.

SefI2 (author)2016-06-07

hello. I'm having a hard time finding 45-75ohm resistors at my country. its not possible to use 100ohm ones? these are abundant in my country

AlexS154 (author)SefI22016-06-08

the light from the LEDs will be much less powerfull. you can use since they ship worldwide

space_eye made it! (author)2016-05-21

chinese doctor ,i made it . thanks ....

AlexS154 (author)space_eye2016-06-03


akiogora (author)2016-06-03

Hi from Kenya! Thank you for sharing this. I also went through a few problems trying to get my design through distribution and all. Now more people can benefit :)

JanuzaB made it! (author)2016-06-02

leyers are incomplete.

if you can help me be happy

AlexS154 (author)JanuzaB2016-06-03

first. please read instructions. i said no light colours , use darker ones like blue , green black.. second , what is your print surface ?did you check your nozzle before starting the print? what is your printing temp? itmay be a clogh as far as i can see. print a test cube or benchy boat to see

AlexS154 (author)JanuzaB2016-06-03

there is smth wrong with you print settings

rescueweasel (author)2016-05-20

Awesome can not wait to make it 3d prints are done waiting on the electrical components. This could be a life saving tool for me. Especially when it comes to emergency line starts on pediatric patients. Thank you!

AlexS154 (author)rescueweasel2016-05-21

can you post your 3d prints? :D .
btw , these are from china ( the guy didn't have dark coloured filament so i guess he painted the print black after he finished )
he also used bigger gauge resistors than the one i suggested and you can see that the space is more cramped
also he used weaker leds. don't make the same mistakes :P
the pictures and details are coming from emails we had

eejcesar (author)2016-05-16

Great desing, simple and very functional

AlexS154 (author)eejcesar2016-05-16


qzwxecrvtb (author)2016-05-15

Alex how much money do you sell from ?

AlexS154 (author)qzwxecrvtb2016-05-15

I've also sent some free of charge but can't afford it right now. if you want and you don't have a printer , you can go to 3d hubs , find a local DIY-er and ask him to help you build one.

AlexS154 (author)qzwxecrvtb2016-05-15

I quit selling them because of high shipment taxes and mostly , now i'm trying to pack up and move in another country and i don't want to get stuck with rolls and rolls of filament and stuff.

Gelfling6 (author)2016-05-15

I Like the design! and well made! I can understand on the cost, I just did a quick search, and seeing them in the $200-$400 range a piece, is horrible! Every time I mention about these vein finders at a hospital, Especially with a friend who is slightly obese, and they always have trouble finding veins for her, the local hospitals seem to want to avoid the idea, and stay with the 'find by eyesight alone' method.. You would think, with this technology available, and LED's costing so little in bulk, that they would be jumping at the idea.. (Personally, I think they enjoy inflicting pain with the try & find method. ha-ha.) Excellent job!

AlexS154 (author)Gelfling62016-05-15

Thanks! At the county hospital in Ramnicu Valcea ( Romania ) , they said smth like that that the device won't do much difference , it won't be that good , but once they saw it in action , they requested 3 or 4 of them ( not sure because i don't remember where my presentation device went )

eilu (author)2016-05-15

This is brilliant. It will help a lot of people.

AlexS154 (author)eilu2016-05-15


space_eye (author)2016-05-15

can you give me some slt file?my wife is nurse too ,i hope i can help thanks

AlexS154 (author)space_eye2016-05-15

i sent you the stl files by mail , if for any reason you can't download them from where i posted them

AlexS154 (author)space_eye2016-05-15

you can find them posted if you click "all steps" in the " printing " step
here :

About This Instructable




Bio: Hi. I am a military automotive engineer passionate about 3d printing area/ cad design / or just about anything in and around this subject. My gf ... More »
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