As a semi professional balloon artist that usually mouth inflates, i wanted a compact, portable balloon pump but wasn't willing to spend the $220 in order to buy a Legenda. So i built my own. I built my pump and then got a zuca bag the next day, and it fits in the bottom of my Zuca PERFECTLY! So, although mine is already built, i'll do my best to explain to you how i built it.

Supplies

1 - Plano shotgun shell ammo can
https://www.academy.com/shop/pdp/plano%C2%AE-shotshell-box#repChildCatid=848804

1 - 12v deer feeder battery
https://www.academy.com/shop/pdp/game-winner%C2%AE-12v-7-ah-feeder-battery#repChildCatid=3747101

2 - 12v air horn pumps
https://www.ebay.com/itm/153319420628

1 - momentary switch
https://www.lowes.com/pd/Hillman-Servalite-16-amp-Single-pole-Black-Momentary-Residential-Light-Switch/1000954982

1 - Rocker switch
https://www.homedepot.com/p/Gardner-Bender-16-Amp-LED-Illuminated-Round-Hole-Rocker-Switch-GSW-50/205971618

1 - 5/8" ID x 3/4" MIP Hose barb elbow
https://www.homedepot.com/p/Everbilt-5-8-in-I-D-x-3-4-in-MIP-Plastic-90-Degree-Elbow-Fitting-Hose-Barb-800419/3008627001

1 - 3/4" chase nipple
https://www.lowes.com/pd/Sigma-Electric-ProConnex-3-4-in-Threaded-Nipple-Intermediate-Metal-Conduit-Compatible-Galvanized-Rigid-Conduit-Compatible-Rigid-Metal-Conduit-Compatible-Conduit-Fitting/1092477

2 - 3/4" rigid conduit locknuts

https://www.homedepot.com/p/Halex-3-4-in-Rigid-Conduit-Locknuts-4-Pack-26197/100111071?MERCH=REC-_-searchViewed-_-308786611;307908141;308378450;308749569;309315795;308786612;308090994;308786614;308786615;307987648;309151549;307913554;308358454;311345491;308786613;308095431;307932230;307961673;312055356;312055366;312055355;309317322;308034940;308033147;-_-100111071-_-N
10' - 1/2" ID clear vinyl tubing
https://www.lowes.com/pd/EASTMAN-5-8-in-x-10-ft-PVC-Clear-Vinyl-Tubing/1000180551

10' - 1/4" ID clear vinyl tubing
https://www.lowes.com/pd/EASTMAN-3-8-in-x-10-ft-PVC-Clear-Vinyl-Tubing/1000365025

1 - 1/4" ID Hose barb tee
https://www.menards.com/main/plumbing/rough-plumbing/pipe-tubing-hoses-fittings-accessories/hoses-tubing-and-fittings/hose-barb-fittings/sioux-chief-1-4-id-barb-nylon-tee/17100210/p-1444442648354-c-8553.htm

1 - inflation needle (i couldn't find a plastic one in the stores, but i found a brass one on amazon)
https://www.amazon.com/gp/aw/d/B07GKRW71C/ref=sspa_mw_detail_5?ie=UTF8&psc=1

1 - red butt splice (but you could just use a wire nut)
https://www.homedepot.com/p/Gardner-Bender-22-16-AWG-Butt-Splice-Wire-Connectors-in-Red-15-Pack-15-121/202522999

8 - electrical female disconnects
https://www.homedepot.com/p/Catamount-Vinyl-Insulated-Female-Disconnect-22-16-50-Pack-TV18-250FD-L/207192654?MERCH=REC-_-searchViewed-_-202204294;202204295;307397178;303993272;303993289;307397026;303993259;207192654;202598514;301734932;301734934;301734974;303994276;303993248;312869178;312869173;-_-207192654-_-N

8' - Red/white bell wire
https://www.homedepot.com/p/Southwire-50-ft-18-2-Bell-Wire-64267201/307335788

2 - heat shrink tubing
https://www.homedepot.com/s/heat%2520shrink?searchtype=text&NCNI-5

2 - 3/4" 8-32 machine screws and nuts

2 - washers for the 8-32s that fit in the bolt bracket of thr compressors

Step 1: Lay Out Your Ammo Can

Pretty straightforward. Put all your parts in your can until you're happy with the layout. In my photo, you can see that i have both of the compressors in the front, the rocker switch to the front left, the battery in the back, the hose coming out the right side, and the chase nipple used for the air intake at the back.

Step 2: Mark Your Holes

Again, pretty straightforward, if you lay your pump out the way i did, you should have plenty of room on the one side for your chase nipple air intake, and your air hose and switch wiring. As for the holes to anchor your pumps, i eyeballed the spot to drill and it worked out for me. Make sure you have everything inside when you mark everything out to make sure you're not going to interfere with where your battery sits or anything. I don't have anything tying the battery down right now, but there's room to add some velcro or something.

Step 3: Drill Your Holes

Drill your holes where you marked them. For the holes for the air intake and the hose barb elbow, you'll need an 1 1/8" hole saw. For the rocker switch, you'll need a 3/4" hole saw. For all three of the bigger holes, a step bit that goes up to 1 1/8" is very effective to get the holes as tight or loose as you want them. As for the holes for the 8-32 screws, you can get away with a 3/16 drill bit, maybe even 1/4". You have more room for error with the two small holes since you have washers for them.

Step 4: Mount Your Compressors, Rocker Switch, and Air Intake Mlm

I didn't want any rough edges sticking out of my pump, so i have the screw heads on the outside of the pump box. In order to put a washer and nut on the bolt, i had to use needlenose pliers. I would mount the compressors before the rocker switch so you don't get in your own way and have to take the switch off just to put it back on again. The air intake chase nipple is in a pretty open spot, so you can really mount it whenever you want using one of your rigid conduit lock nuts.

Step 5: Attach Hoses to Your Compressors

Cut two pieces of your 1/4" ID hose about 6" long. Attach your 1/4" ID hose pieces to both your compressors now, because it will be harder to do after the next step of mounting them. Since we're using 1/4" ID hose, you'll probably have to stretch it to get it to fit. I stretched mine by putting my needle nose pliers inside it and opening the jaws. The hose is stretchy and resilient, so it will shrink back down after you put it on the compressors.

Step 6: Cut and Fish Your Hose.

This step isn't as rigid as the others, and depends on your situation. Put your pump box where you're most likely to use it from (floor, table) and estimate how long of a piece of 1/2" ID hose you think you'll need. For this step, i would err on the side of caution and make your hose a little longer than you think you'll need it. I, personally, would like the option to put it on the floor, even though i might be planning on using it only on a table. Once you get your length determined, fish your 1/4" ID hose and bell wire through the 1/2" ID hose. You might have to use something pretty stiff to fish it through like a straightened out wire hanger. Once you get them both through, you can attach your nozzle to your 1/4" hose (probably by stretching it again) and your momentary switch to your bell wire. You can either use soldier to connect the two, or twist them together in a western union connection. After you connect them, use your heat shrink to hide your connection and to make sure that the wires don't touch eachother and then pull the wire back down into the hose so that the connection is on the inside of the 1/2" hose. To be on the safe side, leave a couple feet of small hose and bell wire coming out of the box end of your big hose.

Step 7: Connect the Hose to Your Box

Push your small hose and bell wire through your Hose Barb Elbow and attach it to your box. Take care not to kink your small hose, and you can even try blowing through it to see if air can get through. Then attach it to your box using your other 3/4" Rigid Conduit Locknut. I put my locknut on backwards so that my hose barb can swivel so that it doesn't kink if I'm using it at a weird angle.

Step 8: Attach Your Hoses Together

Using your 1/4" Hose Barb Tee, connect all of your 1/4" ID hoses together. Shorten your lengths of hose so that nothing kinks. Again, you might have to stretch them using needle nose pliers

Step 9: Wire It All Up!

Using your bell wire, wire it up according to the wiring diagram. I didn't connect a negative wire to the rocker switch. My LED on the switch doesn't come on, but i couldn't get it to work with a negative on the switch. I didn't split the pair of wire going through the big hose, i kept it as a red and white pair, but i did change it to red wires using a butt splice when it comes back into the box so that all the positive wires are red and all the negatives are white. All of my connections are done with electrical femald disconnects. I bent the ones on top of the compressors to 90 degree angles incase they were sticking up too high for the lid to close. It might be easier on your fingers and to get into tight spots if you use needle nose pliers.

Step 10: Come Up With a Handle of Some Kind!

I haven't reached this step yet, so maybe you can figure something out! I was thinking about using Sugru or maybe air drying clay as a handle! Let me know what you come up with!