Building your own R2d2 style astromech droid can get very expensive very fast and very complex to construct. I challenged myself to come up with a way to construct an astromech style droid that is both relatively cheap to build and you do not have to own a machine shop to construct.

Let me introduce A3-8d (problem solving reference intended)

You may have seen glimpses of this robot in a few of my other builds. His function is to be a sort of appliance charging station robot. He also provides storage for electronic devices and tools etc. as I add automation electronics this droid is a test bed for feedback devices and generally a big toy :-)

Offline I've gotten a few questions on the chassis structure and thought I'd share how I built A3's chassis.

So lets get started and make a droid!

Step 1: Plan Your Bot

As with most builds before my droid build I sketched some different designs loosely based on various readily available plastic containers.

I wanted to steer clear of of the classic R2 droid round body/dome top. That image is so iconic if you do not nail it the whole thing looks wonky.

But I did want to keep the 'trashcan' with legs design. This offers plenty of room in the main compartment and the overall feel is appliancey. So speaking of trash cans.... It came to me why not use a trash can. The size would about right. So I found a few cans that I felt had a shape that would not look instantly like a trash can if removed from that context.

The pics above are the droid design and the trash can I settled on.
The trash can is a 7.5 gallon I picked up at Wal-mart ~$8.

Next step was to engineer a way to give a plastic container some sort of load bearing chassis......

Step 2: Skin Over Chassis Layout

For an internal chassis for this droid build I wanted something modular and potentially easy to change if the purpose of the droid changed.

What I came up with was what you see in the pics above. Essentially a custom shelf unit that drops into the skin.
The "shelf unit" and outer skin of the droid can be bonded in the end (builders choice) or if flex ability is your thing leave them separate. This allows you to lift the entire guts of the droid out for trouble shooting and modding etc...

In the pics you see the shelf is basically platforms jam nutted along legs made of all-thread.

I apologize for the lack of pics for constructing the all-thread shelving used for the droid inner chassis I've been tinkering with this Droid for a while and did not foresee an instructable at the time.

But the spark of the idea is what I want to convey more than anything.

The shelving is pretty straight forward
Materials you will need are :

- Several feet of all thread I used 1/4"

If you are not familiar with all-thread it is really cheap ~$2 a stick and can be found at hardware stores, tractor supply, or any of the home improvement big box stores in the metal section. Some auto parts stores keep this but they may want more $$ for it.

- You will need nuts and washers that match your all-thread size and pitch , 2 of each per the # of shelves you are planning.

- shelving material, ply wood etc.. If your going light duty/prop foam board may work.

In my pics you can see I used lexan but only because I had a salvage sheet given to me. It is an excellent engineering material but is pricey $$.

_____Make templates______

A tip for getting the shape of your shelves to match the inner wall shape of your container is to use poster board or card stock. Stack books or something inside your container to the shelf height you want. Work out the shelf profile with paper. Then transfer to foam board. Do a dry fit. Then transfer the foam board templates to your final material.

Step 3: Access Panels and Power Ports

Once the inner chassis is done start thinking about where you want and need removable access panels in the outer skin.

I tinkered with my droid for several months without any panels but removing the entire self chassis of the droid to fix a simple issue gets old.
Plus having handy doors makes the container look and feel more like a droid.

Things needed for the droid access panels:

- Something to measure with
- Permanent marker
- Masking or electrical tape
- Razor knife
- Spool of Utility Hanger strapping
- Hot glue gun and glue
- Small fasteners ~#8

Step 4: Layout Panels and Cut 'em Out

With your marker sketch out a rough layout of what panels you want on the droids container surface.

Over lay this mark up with masking tape and double check your line layouts with a ruler. But keep in mind on multi curved surfaces if it looks right it is right no matter what the tape measure says LoL.

When you are warm and fuzzy about your masked panel layout start cutting out your droid access panels. As always be careful don't cut your digits off.

So how do we attach these???
Now lets make some panel stops...

Step 5: Add Panel Stops

We need panel stops and a means to fasten our panels to the droid skin, this is where the hanger strapping comes in.

Hanger strapping is just a galvanized metal strip with lots of holes. Like the all-thread it is found nearly everywhere and is fairly cheap.

( Follow the pics above) Cut several "three hole" length sections out of your hanger strap. You will need at lease 4 for each panel you plan to make.

Warm up the old hot glue gun and glue your strapping sections one in each corner of the access panel holes as seen in the pics.

Be sure to leave the center hole far enough from the edges to get a fastener through the hole if you plan to use fasteners.
I started off using bolts but they are cumbersome to remove .. I graduated to retainer clips similar to how automotive panels are attached. These are covered in the next step.

Step 6: Latch Tabs and Hinges

To mix up my attachment methods.

To make retainer clips glue strap along opposite edges of the droids panels to function like a tab latch. Slip one side in then flex the panel slightly to 'latch' the other side.

For a simple hinge on One of my longer panels I glued a scrap of tee shirt fabric to the panel and then to the inside of the skin to make a fabric hinge.
Finish the hinge by coating the inside surface to with hot glue. This will keep the cloth rigid.

Step 7: Power Socket

The droid power socket seen in the pics above was constructed from an Aptar Heinz 57 bottle cap.

Simply hollow out the center of the spout half of the cap making a hole large enough to mount an automotive style 12V power socket.

Finish up by cutting a hole in the panel being used to the outer diameter of the 57 cap. Now hot glue the socket frame to the panel and paint.

Step 8: Droid Legs

The legs for my droid are a work in progress but I'll share the direction I'm headed.

The leg frame work seen above is 1" PVC Sch 40 and fittings.

Hanger strap is used to clamp the 'axle' tying the top of the legs together to one of the upper shelves of the inner chassis.

I'm still undecided about leaving the legs all exposed pipe work or covering the leg chassis with a skin.

As for function being that a function of this droid is device charging. The legs will be a good platform for housing all the various battery chargers floating around.

For this I will be adding 110Vac wall outlet supply cord and some sort of function switch for when the droid is plugged in performing charging that is more than what the onboard 12v batteries can handle. When I get the final design worked out I'll share the results.