Mount Designer Tool Guide – How to Use the Rondo Arts Picture Mount Designer
Tool Guide — 2026 Edition

Mount Designer
Tool Guide

A step-by-step reference to selecting apertures, resizing mounts, and setting precise dimensions in the Rondo Arts Mount Designer.

Free to use 3 sections Browser-based tool

Selecting Apertures

Learn how to select single and multiple apertures in the Mount Designer, and move them as a group to build your perfect layout.

Selecting a Single Aperture

To select a single aperture, place your mouse over the aperture to be selected and then Left Click — it will have a blue dotted border around it to show it is selected.

Mount Designer — Single aperture selected
4.987" 3.977"
4.987"

A single aperture selected — the blue dotted border confirms the selection

Tip: Click on any empty space on the mount to deselect all currently selected apertures.

Selecting Multiple Apertures

There are two ways to select more than one aperture at a time:

Option 1

Shift + Left Click

Hold down the Shift key and then Left Click on each aperture you wish to add to the selection.

Option 2

Drag to Select

Hold Left Click on blank space on the mount and drag over the required apertures.

Tip: Shift + Left Click acts as a toggle — use it to fine-tune your selection by adding or removing individual apertures without affecting the rest.

Moving Multiple Apertures

With multiple apertures selected, they can be moved altogether by Left Click hold and drag on any one of the selected apertures. All selected apertures will maintain their relative spacing as they move together across the mount.

Tip: This is ideal for repositioning an entire row or column of apertures without disrupting the gaps between them.

Deselecting Apertures

There are two ways to deselect apertures:

Option 1

Remove / Add Individual

Hold Shift and Left Click on the aperture you wish to deselect — it will lose its blue dotted border while the rest remain selected. This also works in reverse to add an aperture to an existing selection.

Option 2

Deselect All at Once

Left Click on any empty space on the mount. Every selected aperture will immediately lose its blue dotted border.

Changing the Mount Size

Resize your mount by dragging a handle or by typing an exact dimension into a label. Both methods update the mount in real time.

Drag a Handle to Resize

Place your mouse over one of the three drag handles on the mount border, then Left Click, hold and drag to resize. The mount will update in real time as you drag.

Right Edge Drag left or right to change the width
Bottom Edge Drag up or down to change the height
Corner Drag to change both width and height at once
Mount Designer — Right edge handle
7.000" 5.000"
10.000 in
8.000 in

Right edge handle — drag to resize the mount width

Tip: The corner handle is the quickest way to resize when you need to adjust both width and height together.

Type an Exact Dimension

For precise sizing, you can type a value directly into a dimension label. This is done in three simple steps:

  • Step A Left Click on the dimension label you wish to change — it becomes an editable text field highlighted in blue.
  • Step B Type in your required size. The value is entered in whichever unit is currently selected — inches, centimetres or millimetres.
  • Step C Press Enter or Return — the mount resizes to the new dimension immediately.
Mount Designer — Typing an exact dimension
7.000" 5.000"
9.125
10.000 in

Type the new dimension — here the height is being changed to 9.125

Tip: This method is ideal when you need a specific size, such as matching a standard frame dimension. The value is entered in whichever unit is currently selected (inches, centimetres, or millimetres).

Select from Standard Preset Sizes

The Tool Box provides a range of standard preset sizes that can be applied to the mount with a single click. Follow these steps:

  • Step A Click Sizes Shapes in the Tool Box to open the presets panel.
  • Step B Make sure Mount Size is switched to ON in the Select Option section — this ensures the preset sizes apply to the mount rather than the aperture.
  • Step C Scroll down and Left Click the required size. The mount resizes immediately. Preset sizes include A5, A4, A3, A2, A1, 8×10, 11×14, 12×16 and more.
  • Optional Click Landscape or Portrait to toggle orientation — the mount swaps its width and height.

Tip: Changing the orientation will swap the width and height of whichever size is currently selected. Useful for switching between portrait prints and landscape photographs.

Changing Aperture Sizes

Resize your apertures by dragging a handle, typing an exact dimension, or selecting a standard preset — much the same way as resizing the mount.

Drag a Handle to Resize

Mouse over the aperture and three resize handles will appear: one on the right edge, one on the bottom-right corner, and one on the bottom edge. Any of these can be Left Click held and dragged to the required size.

Right Edge Changes aperture width only
Bottom Edge Changes aperture height only
Corner Adjusts both width and height at once
Mount Designer — Aperture drag handles revealed on hover
7.000" 5.000"

Hover over an aperture to reveal the three drag handles — right edge, bottom edge and corner

Tip: The corner handle adjusts both width and height at once, while the edge handles change only one dimension at a time.

Type an Exact Dimension

For precise sizing, click into a dimension label, type the new value, and press Enter or Return — the aperture resizes immediately.

  • Step A Left Click into the dimension label on the aperture — it becomes an editable text field.
  • Step B Type in the required size in the currently selected unit (inches, cm or mm).
  • Step C Press Enter or Return — the aperture resizes to the new dimension immediately.

Select from Standard Preset Sizes

Open the Tool Box and make sure Aperture Size is switched to ON in the Select Option section, then choose a standard preset size from the list. The selected aperture resizes to match.

Important — Auto Shrink: Auto Shrink is ON by default. This reduces the aperture opening by 0.25 inch / 0.6 cm / 6 mm on each dimension so there is a small overlap of the mount onto your image — this prevents the image from falling through the aperture opening. For example, if A4 is selected, the actual aperture opening will be 11.5 × 8 inches instead of 11.75 × 8.25 inches. Turn Auto Shrink OFF if you need the full nominal size.

Tip: Use Portrait / Landscape orientation to swap width and height of the preset aperture size, just as you would for the mount. This is useful when framing landscape photographs in portrait mounts.

Ready to design your mount?

Open the Mount Designer at rondoarts.co.uk and start creating. It is free to use — you only pay for your finished mounts.

Open the Mount Designer