Online Metals Protobox 20 lb Assorted Aluminum Plates, Sheets, and Rods for Metal Casting, DIY, and Crafts Random Aluminum Pieces for Projects and Metalworking

A box of random aluminum stock isn’t glamorous, but in my shop it gets used more than almost any single tool. The Protobox aluminum assortment is exactly that: a 20 lb grab bag of sheets, plates, rods, and the occasional short tube or small ingot. I picked one up to keep near the bandsaw and mill for quick one-off brackets, spacers, welding coupons, and casting experiments. After several weeks of pulling from it, I’m impressed by how often it solved a problem faster (and cheaper) than ordering a specific cut.

What’s in the box

My box arrived well-packed and slightly over the 20 lb mark. Inside was a useful spread rather than a bin-sweep: a mix of flat bar and sheet offcuts in various thicknesses, small plates, round and square rod, and a couple of short tubular pieces. Most pieces were long enough to yield at least one meaningful part or a pair of practice coupons; a handful were small, but still handy for shims, spacers, and test cuts.

Surfaces ranged from mill finish to lightly scuffed shop wear—what you’d expect from clean drops. Edges were mostly saw-cut with minor burrs. Nothing was oxidized or gummy; everything cut cleanly after a quick wipe with solvent.

Alloy identification is the biggest variable. Some pieces were stamped (e.g., 6061), others were unmarked. That’s typical for an assortment like this, and it’s part of the tradeoff for price and variety. If your work depends on a certified alloy/temper, this isn’t the right product. For general fabrication, prototyping, practice, and hobby casting, it’s ideal.

Fit for purpose: machining, fabrication, casting

• Machining: The plate and flat bar machined like standard 6061—predictable chips, good surface finish with sharp tools, and no mystery hard spots. I squared up a small jig plate, turned a pair of bushings from round stock, and milled a camera mount bracket. Expect to face stock to final thickness and deburr edges, as you would with any drop material.

• Fabrication and welding: For TIG practice and light fab, the assortment shines. I cut several “coupons” from sheet and plate to practice fillets and lap joints. Welds were consistent on the marked 6061 pieces. Unmarked pieces welded fine, but I still avoid mixing unknown alloys in a single part unless I’ve tested them. For quick repairs—tabs, guards, brackets—it’s hard to beat the convenience of grabbing a piece that’s close enough and making it work.

• Casting: The occasional small ingot and clean offcuts can be melted for sand casting practice. You’ll get better results if you sort like-with-like and use flux/degassing tablets to reduce porosity. Unknown alloy mixes can cast with more gas and inclusions than known foundry alloys, so I reserve this box for non-critical castings (handles, knobs, simple shapes) and learning exercises.

Quality and consistency

What surprised me most was the thoughtfulness of the mix. Rather than a pile of unusable slivers, the assortment favored practical dimensions—short lengths of rod suitable for turned parts, plates thick enough to face and drill, and sheet stock useful for gussets and covers. I did receive a couple of hollow pieces (short tubes), which I appreciated for spacers and standoffs, but if you’re expecting only solid round, keep in mind the mix is random.

Flatness was acceptable for drop stock. Thicker plates had a whisper of bow that a vise and light facing corrected. Sheet pieces were flat enough for fabrication without heroic measures. Overall, the material felt like genuine shop drops, not scrap.

One minor gripe: a few pieces had faint ink stamps that were partially cut off, leaving me guessing between two alloys. Not a deal-breaker, but it underscores the point—don’t buy this expecting traceability or certificates.

Value and who it’s for

There are two reasons I’d choose a box like this over ordering specific cuts:

1) Time and flexibility: For rapid prototyping and maintenance tasks, having varied stock on hand speeds everything up. Instead of redesigning around what I have or waiting for an order, I can often pick a near-match and get the job done.

2) Cost per pound: Buying one-off lengths and small plates from retail metal suppliers adds up quickly—cut fees, shipping, and minimums. A well-curated assortment reduces waste and typically lands at a friendlier cost per pound for small shops and hobbyists.

This box is an easy recommendation for:
- Makerspaces and school labs that need safe, small-format stock for projects and practice
- Maintenance techs who improvise brackets, guards, and spacers
- Hobby machinists and welders building skills and small fixtures
- Prototype-focused shops that iterate quickly and don’t need certified alloys for every part

It’s not the right fit if you require:
- Certified alloys and full traceability
- Repeatable, identical pieces across multiple boxes
- Dimension-specific stock for tightly toleranced production work

What I’d change

• Clearer alloy labeling: Even a simple color dot scheme for common alloys would be a big win. I know this is a drop assortment, but a little more identification would further increase utility.

• Option for mix bias: A selection toggle like “more plate,” “more round,” or “no tube” would help buyers aim the random mix toward their typical use.

• Include a simple material ID card: Quick tips for distinguishing common alloys and guidance for casting/degassing would help newer users get better results.

Practical tips to get the most from it

• Sort on arrival: I separate plate, sheet, round, and tube, then label thickness/diameter and any visible alloy markings. Ten minutes spent organizing pays off later.

• Face before measuring: For mission-critical dimensions, take a skim cut on both sides of plate/flat bar to eliminate saw marks and minor bow.

• Keep like-with-like for casting: If you’re melting, don’t mix unknown alloys indiscriminately. Expect more dross and porosity than with foundry alloys; flux and degas accordingly.

• Test welds on coupons first: If the alloy isn’t marked, run a quick practice weld and bend test on a small offcut before committing to a part.

• Design around the drawer: When possible, adapt quick projects to the stock you have. Choosing thicknesses and profiles that match your assortment drastically cuts build time.

The bottom line

The Protobox aluminum assortment earns its keep in a small shop. It’s a practical, no-fuss way to keep a variety of usable aluminum on hand without overpaying for small cuts or waiting on shipments. The pieces in my box were clean, sensibly sized, and genuinely useful across machining, welding, and light casting. You give up alloy certainty and exact dimensions in exchange for value and immediacy—but that’s the point of a drop assortment.

Recommendation: I recommend it for hobbyists, educators, maintenance techs, and prototype-focused shops that thrive on flexibility and need a dependable bin of aluminum ready for cutting, welding, or machining. If you require certified alloys, identical repeat pieces, or tight dimensional control out of the box, look elsewhere. For everyone else, this is the kind of “quiet tool” that saves time, stretches budgets, and keeps projects moving.