01
Watercolor paper
For watercolour, gouache, and ink washes. Look for 140 lb (300 gsm) cold-press — heavy enough not to buckle when wet. Hot-press for fine detail.
Make your first card
How to make an ACEO.
There's exactly one rule — finish at 2.5 × 3.5 inches — and infinite freedom inside it. This guide takes you from a blank scrap of cardstock to a signed, sealed, ready-to-sell miniature, whatever your medium.
Step zero
Choose your substrate.
The "substrate" is simply what you paint or draw on. Match it to your medium and you're halfway to a good card.
02
Bristol board
Smooth and rigid — ideal for pen & ink, marker, and colored pencil. Smooth (plate) finish for crisp lines; vellum finish for a little tooth.
03
Mixed-media cardstock
A tough all-rounder that takes light washes, pencil, marker, and glue without falling apart. A forgiving first choice.
04
Illustration board
Thick and sturdy for acrylic, collage, and heavy mixed media. Won't warp under glue or built-up paint.
Whatever you choose, aim for something stiff enough to survive shipping. Flimsy paper bends in the post; cards should feel like, well, a card.
Cut to 2.5 × 3.5
Get the size exactly right.
Accuracy here is what makes a card a card — buyers expect it to slide into a standard sleeve.
- Mark 2.5″ wide × 3.5″ tall (portrait) or 3.5 × 2.5 (landscape)
- Use a metal ruler and a sharp craft knife on a self-healing cutting mat
- A guillotine or paper trimmer gives the cleanest, most repeatable edges
- Make a reusable template or pre-cut a stack so every card matches
- Many artists paint first on a larger sheet, then cut down to the best 2.5×3.5 crop
Pick a medium
Eight ways to fill the frame.
Every medium behaves a little differently at miniature scale. Here's what to expect from the popular ones.
Watercolor
The classic ACEO medium. Work small and loose; let colours bloom. Use a fine round brush and limit your palette so the tiny format doesn't get muddy.
Ink & pen
Fine liners or dip pens for crisp line and cross-hatching. High contrast reads beautifully at card scale. Pairs perfectly with a light watercolour wash.
Colored pencil
Forgiving, portable, and detailed. Build colour in light layers and burnish for depth. Great for animals and portraits.
Acrylic
Opaque and quick-drying — good for bold colour and texture. Use a little flow medium and a tiny brush so the paint doesn't overwhelm the surface.
Gouache
Matte, vivid, and re-wettable. The opacity of acrylic with the handling of watercolour — a favourite for clean, graphic ACEOs.
Pastel
Soft or oil pastels for painterly colour and blending. Work on toothy paper and always fix the finished card to stop smudging.
Collage & mixed media
Layer papers, washi, stamps, and paint. Keep glue thin and the surface flat so the card still fits a sleeve. Endless texture, low pressure.
Digital prints
Create digitally, then print as a numbered giclée edition on quality card. Label clearly as a print — this is the "Editions" in ACEO.
The basic workflow
From blank card to finished piece.
1
Prep your card
Cut (or pre-cut) your substrate to 2.5×3.5. For wet media, lightly tape the edges to a board to stop buckling.
2
Sketch lightly
Block in your composition with a soft pencil. At this scale, one clear focal point beats a busy scene.
3
Build your layers
Work background to foreground, light to dark (or dark to light for opaque media). Let each layer dry before the next.
4
Add the details
Switch to your smallest brush or finest pen for highlights and accents. A few crisp marks bring the card to life.
5
Sign & title the back
On the reverse, write the title, medium, your name, the date, and — for prints — the edition number (e.g. 3/25). Add "ACEO" and the size.
6
Seal it
Apply a suitable fixative or varnish for delicate media (pastel, pencil, charcoal). Let it cure fully before sleeving.
The back of the card
What to write on the reverse
- The word ACEO and the size (2.5 × 3.5″)
- Title of the piece
- Medium (e.g. "watercolour & ink")
- Your name / signature and the year
- For editions: the edition number (e.g. 3/25) and "giclée print"
Keep the front clean — most artists sign small on the front and put the full details on the back.
Sealing & fixative
Protecting the finish
- Pastel, charcoal, graphite, colored pencil — use a workable or final fixative to stop smudging
- Acrylic — an optional matte or satin varnish deepens colour and protects the surface
- Watercolour & gouache — usually left unsealed; a sleeve is protection enough
- Always spray in light coats, in a ventilated space, and let it cure before sleeving
Skip these
Common beginner mistakes.
Every ACEO artist learns these the hard way. You don't have to.
Wrong size
Anything but 2.5×3.5 isn't an ACEO. Measure twice; cut once.
Paper too thin
Light paper buckles when wet and bends in the post. Use card-weight stock.
Too much detail
Cramming a full landscape into a tiny card muddies it. One strong subject wins.
Forgetting the back
Unsigned, untitled cards look unfinished to collectors. Always label the reverse.
Skipping fixative
Unsealed pastel and pencil smear in transit. Seal delicate media before sleeving.
Bad photos
A dim, colour-cast photo sinks a listing. Shoot in daylight against a neutral background.
You've got this
Gather your supplies.
Know your medium? Next, stock your desk. Our buyer's guide covers paper, paints, brushes, fixative, and the sleeves and mailers that keep finished cards safe.