Paul

You may choose a colourful style for the custom coupon message, or wrap the message in your own CSS class container.
It’s also possible to hide the default message from Woocommerce so that only your custom coupon message is displayed. 
(the plugin uses inline CSS to hide the default Woocommerce message).
Take a look at the screenshots for the coupon edit screen with the plugin enabled and some examples.
The meta box was implemented using the technique described on this blog post: 
http://wp.smashingmagazine.com/2011/10/04/create-custom-post-meta-boxes-wordpress/
The message styles were generated using this tool: 
http://www.bestcssbuttongenerator.com/

Woocommerce Custom Coupon Message

This plugin adds a meta box to the coupon edit screen where you can make your own customized coupon message.

runthings.dev

This plugin allows you to restrict the usage of WooCommerce coupons based on user roles, including guest users.
You can specify which roles (including guests) are allowed or excluded from using a coupon, providing more control over your discount strategies.
<h4>Features</h4>
<ul>
<li>Restrict coupon usage based on user roles.</li>
<li>Option to specify both allowed and excluded roles.</li>
<li>Support for guest users with a “Customer Is A Guest” pseudo-role.</li>
<li>Customize the error message via a filter.</li>
</ul>
<h3>Filters</h3>
<h4>runthings_wc_coupons_role_restrict_error_message</h4>
This filter allows customization of the error message shown when a coupon is not valid for the user’s account type.
For detailed documentation and advanced examples, see the <a href="https://github.com/runthings-dev/runthings-wc-coupons-role-restrict#filters" rel="nofollow ugc">full documentation on GitHub</a>.
Parameters:
<ol>
<li><code>$message</code> (<code>string</code>): The default error message, e.g., <code>"Sorry, this coupon is not valid for your account type."</code>.</li>
<li><code>$context</code> (<code>array</code>): Additional context for the error, including the coupon, user roles, and guest status.</li>
</ol>
<code>$context</code> object format:
The <code>$context</code> array contains the following keys: 
– <code>coupon</code> (<code>WC_Coupon</code>): The coupon object being validated. 
– <code>is_guest</code> (<code>bool</code>): Whether the current user is a guest (not logged in). 
– <code>user</code> (<code>WP_User</code>): The current user object. For guests, this will be an empty user object. 
– <code>allowed_roles</code> (<code>array</code>): Roles explicitly allowed to use the coupon, in the format <code>[role_id => role_name]</code>. 
– <code>excluded_roles</code> (<code>array</code>): Roles explicitly excluded from using the coupon, in the format <code>[role_id => role_name]</code>. 
– <code>effective_allowed_roles</code> (<code>array</code>): The final calculated roles allowed to use the coupon, after considering exclusions, in the format <code>[role_id => role_name]</code>. This is the set of roles that can use the coupon.
<h3>License</h3>
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, see <a href="http://www.gnu.org/licenses/gpl-3.0.html" rel="nofollow ugc">http://www.gnu.org/licenses/gpl-3.0.html</a>.
Icon – Discount by Gregor Cresnar, from Noun Project, https://thenounproject.com/browse/icons/term/discount/ (CC BY 3.0)
Icon – restriction by Puspito, from Noun Project, https://thenounproject.com/browse/icons/term/restriction/ (CC BY 3.0)

Coupons Role Restriction for WooCommerce

Restrict the usage of WooCommerce coupons based on user roles.

Woocommerce Custom Coupon Message vs Coupons Role Restriction for WooCommerce